Hello. I am a Diamond Support player but frankly, neither you nor I care who I am so lets get on to the star of this show.

What Is Rell?
She is a tank support champion. No surprise here. As with all new League champions, there will always be some comparison to other champions along with their abilities and playstyles so let's compare so you get an idea if you want to play her.

Kled

With her charging in and having multiple forms, she is reminiscent of an older off-meta support, Kled. Although each engage is quite similar, the clear difference between the two is damage. To put it bluntly, Rell does not do damage. While support Kled can hold his own with dueling, pushing and ganking, Rell -alone- cannot do any of that effectively. Furthermore, while Kled speeds up to fight dismounted, Rell speeds up while mounted. She is not a tank support capable of solo pressure.

Taric
Lets next discuss a fellow mineral tank, Taric. Taric and Rell share the link mechanic in their kit where they increase their linked partner's defensive stats as well as being able to stun where they are and where their partner is. The difference between these two, once again, comes to their fighting potential. While Rell provides a better engage compared to Taric with both Ferromancy's mobility as well as instantly stunning as opposed to a wind-up stun, she provides significantly less healing than Taric can while having slower auto attacks due to their passives. Once more, she is slightly surpassed by damage.

Volibear
Let's, once again, compare her engage. Her engage is her W which has two different forms. She either jumps for a knockup or she gets on her horse and flips her auto attack target behind her. She can also CC her opponent whilst they are in the air. Sound familiar? Indeed, pre-rework Volibear has come once again to the support role and this time, it does peanut damage. Want to guess my gripe here?

Leona
With all those downsides, how could she be viable? Let's finally compare her to what I believe to be the most similar playstyle and kit, her fellow blond tank but with a helmet, Leona. Both have 3 CCs and 1 utility in their kit (yes, Rell has 2 in her W but we're counting that as 1 button). They both engage by moving into the enemies position and will likely land a stun if their gap closing engage works. Finally, they are both screwed if their lane partner just sorta dozes off during the engage. Let's now go to their passives. Each ability of Leona's means her lane partner will deal a bit more damage in a fight. Rell will steal 10% defensive stats as well as a bit more damage per auto attack at the cost of higher windup time (slower attacks). While this is good later on against enemies who built tankier, Leona comes out on top for the early 2v2 phase.

With her being outmatched in every task by another champion, why would you play Rell ?
Let's look at the pros and cons.

PROS	CONS
+ Shield Breaker + Amazing peel + Good engage + Playmaking potential + Tanky and provides defensive stats to linked + Anti-Tank + Instant CC + Slow speed dismounted	- All or nothing engage - Difficult to reposition if W is on cooldown - All forms of CC are a counter. - Low damage - May be the worst champion to move alone, rivaling Yuumi - Slow speed dismounted

From this, you can see that Rell is primarily a peel tank who can also have a place in making wombo combos. While she may have heavy deficiencies alone, her strengths lie elsewhere. So long as she has an ally by her side, any enemy that your group comes by will be sucked in and will never leave without either a flash or leaving their corpse.

Why is slow slow move speed both a pro and a con? This accounts for some mind games. As with the current state of League, if a champion is too slow, it simply feels bad to play. Rell pushes this to the extreme with a 250 base move speed dismounted, 35 less than dismounted kled. Few players experience playing with or against this type of slowness that was not of their influence. The con is obviously the low move speed but the pro is that you bring your opponent to your tempo and have the opportunity to decide when to break it. Ferromancy: Mount Up provides both the return to a normal base move speed as well as increased move speed topped off with further increasing when approaching enemies. Without any shiny animations, you suddenly gain approximately 200 move speed and are charging towards an enemy who overstepped feeling too confident from your dismounted hobbling. There's simply nothing better than catching someone unprepared and just going to town on them.


You want to play the hero that jumps in to save ally? Perhaps you want to charge into the enemy team and laugh with low health while the enemy corpses surround you sealed by your metallic storm. Then Rell is the champion for you.

I personally prefer Aftershock as engaging usually affects 1 champion so the other one is usually wailing away at me. The extra resistances from aftershock helps mitigate some damage and also deal a bit more damage. Guardian is a decent second choice. I feel the current guardian is rather unreliable when you try to activate it by proximity but that's just a personal preference.

Shield Bash is the preferred choice here for the defenses it gives and the extra bit of damage it provides. I take font of life if my goal is to maximize my ADC's damage.

All three are good for different styles of Rell. Bone Plating is good for the constant trades and is the likely default choice. Second Wind is helpful when you take constant light damage. Conditioning just maximizes the resistances that Rell can have.

More health is always good and Overgrowth provides a bit.


With all the fighting you want to be doing, you will be low of health. Biscuit Delivery helps lower the risks of your trades with free potions

Cosmic Insight. Summoner spell haste? More flash combos. Easy choice.

Break the Mold [Passive]

It shines around mid-late game when tanks start building some resistances. Early game, its lackluster stealing about 3-4 resistances on top of about 11-15 more damage per auto attack. This may be phenomenal if she didn't have the second slowest attack speed just after Graves.

Shattering Strike [Q]
This ability is, in a word, underwhelming. It can break shields which is great assuming the enemy team even has shields. It does 50% less damage to those after the first target and even then, it has very low base damage. Also, it applies Break the Mold but only to the first target hit. At max level, the first target hit will take less damage than a max level Soraka q and will likely heal less. Each point into this ability will increase the heal amount by an astonishing amount of 5. Calling this ability disappointing is giving it too much credit.
This should only be used to break shields in a fight or to lightly tickle your opponent when your linked ally is at about 50% health. Any other uses is a waste of mana.


/ Ferromancy: Crash Down/Mount Up [W]

This is your key ability as it will literally decide if you live or die whenever you use it. A well aimed Ferromancy - Crash Down may give your team that satisfying full team combo. A poorly aimed one will almost always ensure that you have either died to the enemy bot lane just pelting you with no remorse or, at best, came out of it with 1/4 of your health left. Crashing down also provides a shield that maintains while she is dismounted so that may be helpful to deal with some poke.

Dismounted Rell has a slow move speed of 250 move speed. Ferromancy: Mount Up provides a good burst of speed as well as a flip. This, I believe, is the primary ability you should be using to engage as you not only displace your target, you come out of it mounted meaning you will still have some capabilities to reposition around as the battle progresses.

All this is not to say you shouldn't crash down to engage. If you have the opportunity and you're certain it lands, use it. My opinion here is based more on reliability as a failed mount charge is less disastrous than a failed crash down charge.

Attract and Repel [E]
This provides resistances for your ally as well as a safe aoe CC for them. This is reliable in that it stuns both the area between you two *** well as in a circle around both of you
Used aggressively, this is a nice CC to ensure your ally, who is chasing, can freely hit their target for a little bit. The stunning part being basically an instant cast is very helpful to get things done then and there. The biggest downside to this ability is that when switching linked ally, there is a non-reduceable 2.75 second cooldown. When it comes to assassins, this time frame may be deadly for your backline so pre-emptively prepare for that if the situation seems likely to occur.

Magnet Storm [R]

Very much your "You shall not pass" move. While the first activation counts as 1 proc of immobilization, the drag portion does not. The drag also does not mitigate any gap closer abilities like dashes or blinks so it should not be relied on to lock down targets. The main use will be for the activation pull as a light knockup CC with a very small cast time.

Why is there a section for this? It is to highlight some of the core weaknesses in her abilities that dramatically hinders her ability to perform and should be avoided if there is even the possibility of other things happening on the map.

Most consistent builds of Rell are some tank variant and as such, her AP scaling on her abilities are, for the most part, irrelevant. While the scaling ranges mostly between 30%-50%, the most important part of part of any skill is the ability to have it hit it's target.

When solo shoving a wave, Rell has 2 abilities, Shattering Strike Q and Ferromancy - Crash Down W. Furthermore, ferromancy only does AOE damage when your crashing down so you need to wait for twice the cooldown before using it again. Why not Full Tilt? You cannot activate Full Tilt alone. You cannot activate the stun damage portion without being linked to an ally and she cannot link to herself. This renders the ability useless as you literally cannot use it alone. In addition, her Q Shattering Strike deals reduced damage to all but 1 target which hinders her pushing ability. To top it off, she has low attack speed.

All this culminates in terrible pushing power that other champions laugh at. Not only do these weaknesses hinder pushing, she also cannot duel any champion that may come to stop her. There are very few champions that would lose to her 1v1 on even terms. Off the top of my head, the only champion she has a chance of beating is Yuumi and if she does not die from the initial combo of W auto R Q, Yuumi will very easily escape with her CC abilities and her significantly higher movespeed compared to dismounted Rell

Boots

Not much to say about the defensive boots as it's pretty self explanatory. TLDWrite, you want more defense of that type. This bit will talk about why Mobility boots

Mobility Boots are my default choice here. Why not Boots of Swiftness you may ask? From my experience, Boots of Swiftness are simply not a good choice for boots. The purpose of swiftness is to have a better base move speed to supplement dismounted Rell's move speed or to have a better charge mounted. I believe that trying to fix dismounted Rell's move speed is a mistake for the simple fact that she simply does not do anything special while dismounted. Her role as a vanguard is to hold the line but any champion who can dash out of your ult drag will get out regardless of your speed. Boosting her low move speed to the lower end of the 300's simply does not help in chasing down enemies that pass your guard. The slow resistance is nice but what will that do? Cripple your already crippled legs? It is simply better to be prepared earlier for a fight rather than be useless during the fight.

Mythic

Imperial Mandate. Since Rell has such a similar style to Leona, why not make her a Leona? Your CC abilities will each do just a bit more damage along with the procs your ally will be providing. With a little bit of HP, some AP and some move speed for both of you, every engage will hurt. Note that your R will only proc 1 instance of this during the initial cast.

Locket of the Iron Solari. Your the only tank/engage on your team? Looks like a game with a lot of teamfights? You may want the locket to maximize on tankiness.

Shurelya's Battlesong. Really lookin' to run around the map? Pick up the battlesong and lead the charge to your team's victory (or demise).

Core

Zeke's Convergence. Once again, make that Leona dream come true. 8 seconds of better overall damage at the low, low cost of being in auto attack range? Sign me up. Bit of health/mana and armor to always helps.

Knight's Vow. Is the damsel, once again, in distress? Have some fear as they take 15% less damage and you gain 35% move speed towards them if they have less than 50% health. A few moments of survival means a few moments for you to have a chance to save them.

ADC AMP

Ardent Censer. Shattering Strike is pretty useless. Let's make it useful. Give them some more attack speed and more on-hit damage.

Redemption. Ally needs some more survival but your a bit too far? Perhaps you've died from a bad engage? No problem. Drop the heavens on their head with some fat heals and burn the enemy for daring to tread your land. Even in death, you shall encourage your allies.

Staff of Flowing Water. Same reason as Ardent Censer. They wanna go fast? Tickle the enemy and both of you gain some move speed and a bit of AP.

Resistances

Randuin's Omen. Got some enemy crit you wanna deal with? Pick up a randuin's.

Gargoyle Stoneplate. There is no better hybrid tank item than this. Good resistances for both that further increases to an extra 15% for each? That linked ally of yours looks quite beefy. Slap on a activatable shield and a size increase to make your R suck just a bit wider.

Dead Man's Plate. You want armor? This has armor. You want speed? This has charge speed. You want a slow? This gives mounted you a slow. Overall, good anti-AD item.

Thornmail. Anti-heal. Yup.

Abyssal Mask. Health and magic resist. CC anyone and they suddenly take 10% more damage. That's pretty good.

Force of Nature. Health, magic resist and move speed. Totaling 80 MR and 30 + 5% move speed.

Spirit Visage. If your really gung ho about that healing thing, might as well.

Honorable mentions

Bami's Cinder. You may be tempted to take one of the bami mythic items. It is certainly a choice. Main downside to it is the inability to stick to enemy champions if you dismount. Best used mounted.

Warmog's Armor. While this is nice, Rell scales better with resistances as it helps better in ensuring the survival of your team. This item is more of a "I have too much money" item for Rell.

Laning Phase

To start at level 1, look for an opportunity to land a Ferromancy - Crash Down for a trade. Do not be discouraged if you can't as even this trade is pretty risky. Main goal here is to either force the enemy to blow a flash or at least all their potions. Know that if you do this, you will likely come out worse for wear but if the opponent has less health percentage wise, its a win. Level 2 is when you should be looking for kill engages.

During laning phase, it is best to remain dismounted. Although you will have incredibly low movement, it's not like your going to be doing insane mechanical plays at level 1-3 with no items. There are 2 reasons to be dismounted.

The first is that you maintain a shield that stays on until it either breaks from damage or until you remount. You may take a lot of poke in lane and that's ok. It is, unfortunately, a big weakness in Rell so use the shield to soak up what you can and refresh it if nothing is happening.

The second is that Ferromancy: Mount Up is a reliable engage. with move speed that surpasses all this early on, it can flip an unsuspecting opponent into your ally and chained with Full Tilt for a solid burst of damage. On top of this, you will be mounted so your move speed will be able to keep up with the fight. Should the fight drag on and turn sour, you would likely have Ferromancy - Crash Down up and the opponents, likely having used most of their skills during the fight, will be less likely to avoid crash down which will also provide you the shield for even longer fighting.

Ferromancy: Mount Up is also helpful in disengaging from an enemy gank. Suppose you and your ADC have over-pushed and the enemy jungler is ganking. Ensure you are linked to your ADC and position yourself so that if the enemy jungler goes on your adc, you can activate Full Tilt followed by Ferromancy: Mount Up to stop and flip the enemy jungler away from your ADC. You are also mounted now so you have the opportunity to escape as well.

If you see the opponent is vulnerable to a Ferromancy - Crash Down, then feel free to also engage. Although is unlikely for you to chase down the opponent, it will provide a good burst trade that is in your favor due to the stun and shield you provide.

This pattern of engage and push continues even past level 6. At level 6, you have Magnet Storm which is just another CC tool in your arsenal. This simply holds your victim in place and makes your oppression just a bit stronger.

To summarize Rell's goal in this phase, it is to interrupt, interrupt and interrupt.

This will depend on game flow. But more often than not, you'll be following your ADC or your jungler around the map to capture objectives.

Going with a jungler? Chain up that CC and lock down your victim.

Paired up with your ADC? Ready that E key if they ever get jumped on and prepare to dive in to hold off aggressors while your ADC goes to town on them.

Who you pair with depends on who you believe can carry the game so it could be any role.

Thanks for reading.
I'll update this if there are any significant changes to the champion or items or if there is some new build that completely blows our understanding of Rell out of the water.

Good Luck on your Path.