Why the Rune Summon Aery ? Playing alistar means, you always start with W first, its your main DMG Spell and you always combinate W > Q. Summon Aery dmg up every spell you hit and the reason having it with alistar is that you always heal your teammate when he killed an enemy or 7 minions. Playing in a lane with that Rune means everytime he gets an heal up he gets an shild. Thats pretty helpfull if he wants to start an offensive couse he dodge 1 shot and can work an better posiition in lane what gives you also the ablity order that you dont run into dust with your skills.

Another reason is playing with absolute focus and nimbus cload and also gathering storm. We get very deadly with our ablitiys from start on and over time. Your able after you activated any summoner spell to run away after you set your skills on or to land the E Stun.

That we heal passive makes absolute focus an great rune for us.

We always need 40% magic penetration with alistar just keep that in mind. We dont wanna start at first with this because its not an support item at all. And to geth healthy and ofc to slow our enemys with e ofer time is great.

Alistar isnt a tank at all his R is the main reason while playing him like a tank. To have a few armor and magic dmg reduced item on him help us to cast our R pretty well for a good time duration.

Thats it enjoy your Healing CC Monster =).

Have fun.