Lvl 1.: Conjurer's Pursuit. This hero eat mana. If you wanna stay on lane for long time and supp like hell or solo exp farm & ganks, mana reg is just needed.

Lvl 4.: Amplified Healing. For more op supp.

Lvl 7.: Burden of Guilt. The stun is short timed so slow is a really good help to ur mates to kill the enemies.

Lvl 10.: Divine Storm. Just op aoe stun. Can break some ulti like Nova's and with a good positioning you can carry teamfights.
B.: If you have a good team with a pro dps: Divine Shield. Kayle ulti from LoL. Love it. Just be sure you use on the good hero. I use when my mate on low hp and i try to keep him alive in fight as much as possible. But many players see ourself on low hp and just run as a blind braindead... So be care use it on the good players not the most dps actually.

Lvl 13.: Shrink Ray. Awesome debuff on the enemy dps. Sometime i choose Spell Shield. If your team is leading but the enemy is always focusing on u in teamfights of course because ur a fckin op support, better pick this to save ur *** a bit too.

Lvl 16.: Imposing Presence. Actually the enemy team should focus on you. But your an op healer tank, not easy to kill. With this passive you also helping to your mates while u do nothing and just focused by enemies.

Lvl 20.: Storm Shield. A big help in teamfights. Shielding all of your mates for a short time.
B.:Bulwark of Light. Kayle ulti for 5 sec and reduced CD. No comment. Macho.

Early Game: I like to go on midlane because easy to gank on top/bot and ur dps is good in early games. Just rushing out from the bush stunn enemies heal mates and dps with ur w if neccessary.

Mid Game: On midgame your a full support. You should stay in the first lane with the tanks. Focus with your stunn and just keep alive your mates.

Late Game: Your a full support with stun, good heals and ur an offtank also. You will be the most important in teamfights. You absoludly can carry a match.

Positioning is very important to you. Always go on first lane with tanks cause ur an off tank healer too.
Really important to use your w (Holy Radlance) correctly, because this is an aoe heal but its a skill shot, not a target skill. And you can heal all of your team on way.

Try to be a snail. If enemy start to focus on you thats good. Ur a tanky healer.

After u died your trait passive (Eternal Devotion) keep u on lanes for a short time. You can use a heal skill only but thats awesome. 1 sec CD!!!! and healing a lot.