I've been playing support tanks for quite a while, and find them to be very efficient. What is a support tank? Pretty simple: a support champ built like a tank. For instance, Sona, Lux, and Soraka all make great support tanks. Enemy teams usually attempt to focus support/caster type champions, meaning you. With your healing/shielding and a bunch of armor/mr, you're nigh impossible to kill. So while they are busy trying to kill you, your team is killing them. Common items for a support tank:
Archangel's Staff - All support champs need a little bit of ability power in order to function well as a support. That's where this comes in. In addition, it greatly boosts the amount of mana you have, as well as the regeneration of that mana. A support with no mana isn't a good thing.
Lucidity Boots - The 15% CDR is unbelievable on these champions. Your abilities are what allow you to play that supporting role, so the more you can use them, the better you will do. That being said, if you find yourself up against a CC heavy team, merc treads are a viable option.
Glacial Shroud - Provides the rest of your CDR. Also provides a large amount of armor and mana.
Frozen Heart - If you're up against a bunch of auto-attackers that rely on attack speed, this item is your best friend. Provides a ton of armor, cdr, mana, and debuffs enemy attack speed by 20%.
Spirit Visage - If you're using Sona or Soraka against an AP heavy team, this item is a great substitution for that glacial shroud.
Hexdrinker - If the enemy team has a nuker, such as Annie or Nunu, this item will save your ass many times over. It's always funny when you buy one, then they attempt to nuke you. The added attack damage is a plus.
Guardian's Angel - If they are still managing to kill you every team fight, get one of these. It might prevent you from dying, or it might bring you back to life. Sometimes you'll be able to escape, other times it will turn the tides of the battle, and others it will just allow your teammates to get away while the enemy waits for you to revive. Saving teammates is a supports job, you know.
Force of Nature - This is a great item for Lux. Coupled with her shield and snare, you can be saved by that hexdrinker you bought, get yourself out of the danger zone, then hop back in when the time is right. And no one ever complains about extra movement speed.
Rabbadon's Deathcap - Buy this when you feel you are tanky enough. It triples the AP you had from that AA.
Zhonya's Hourglass - I've never used this item, but it doesn't mean I won't. AP and armor, with the stasis effect that everyone loves (or hates).
Abyssal Scepter - If both teams are rather reliant on AP, this item is a godsend.
Lich Bane - Sometimes I splurge for one of these. Usually with Sona. Allows you to dish out a lot more damage, while providing a bit of magic resist and movement speed.
Just remember, the more you focus on AP, the less tanky you will be.
Anyway, go play yourself a few games, see how you like it. Works wonders for me, so I figured I'd share.
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