Yo,
name's Špa.
(reads as Shpa]
I'm Diamond ADC and I used to be one of the best Aphelios Players on server EUNE. Eventually stopped to play cause I got bored of the game, but now I'm back and playing mid. Aphelios was my OTP and most favorite ADC and he still is.
My friend asked me to teach him and explain him, how even this champion works, how to play him and be useful for your team.

I'll try to explain everything, why this, why that...
Basically, I'll go in-depth.

Also, this is my first guide.
Don't expect anything fancy, just detailed information regarding
Hopefully it will be helpful and my English won't be much broken.

Important information I'll colorize.

You could imagine Aphelios as something as a rattling gun.
He pretty much works the same way.
Deals high dps but doesn't have any mobility at all.
Which is his biggest weakness.
For this reason he can be easily oneshoted by any burst champ e.g Kayn, Kassadin..

Compared to other ADCs I daresay that, he's one of the hardest ADCs in the game.
Yeah, he's just another right-click champion like any other ADC, but for Aphelios players that really is not the only case.

In fact, out of all ADCs he's the most complicated one to learn, understand and carry the game with.
For playing him usefully it requires game knowledge and especially, a lot of game experience as an ADC.

You must know how to position in fights (hardest and most cruical part for Aphelios).
You must know what each of your weapon does.
You must know what you can afford with your current loadout (experience through games).
You must know all weapons combination (what they do together, how to combine them..).

And through all these things we'll go in this guide.

Firstly, let's look on Cons and Pros, so you can create some image of him.

5 weapons each has special effect and 50 durability. Autoattack removes 1 durability, Skill removes 10 durability, Ultimate removes 0 durability. He has always equipped two weapons and after one runs out of durability it is automatically swapped to another. Order is as following: Green -> Red -> Purple -> Blue -> White or rather Calibrum, the Sniper Rifle -> Severum, the Scythe Pistol -> Gravitum, the Gravity Cannon -> Infernum, the Flamethrower -> Crescendum, the Chakram It doesn't neccesarily mean that you will always have for example Calibrum, the Sniper Rifle and the weapon behind it Crescendum, the Chakram or in front of it Severum, the Scythe Pistol. You can even have Calibrum, the Sniper Rifle and Infernum, the Flamethrower. It all just depends on how you swap your weapons.

Green or Sniper Rifle (depends on you) is literally what it sounds like. Passive effect: increases your attack range = same as Caitlyn's. Poking enemy in the laning phase. Easy positioning in teamfights. Good in early game also late game.

Skill- Moonshot Shoots a projectile in one lane. If you hit then you're able to hit the enemy again. Then there takes place a secondary weapon. If you hit an enemy with Skill and AA him then the effect from the secondary weapon will apply (on that AA. The hit after skill hits is always counted as AA).

Combinations Green - Red Calibrum, the Sniper Rifle - Severum, the Scythe Pistol -> Moonshot and AA => Heals you. Green - Purple Calibrum, the Sniper Rifle - Gravitum, the Gravity Cannon > Moonshot and AA => Slows enemy. When you swap to secondary weapon and press skill, it will root him.