Your abilities help your team. You can heal, you can protect allies with shields, you can speed them up or give auras out that help them. Your NOT gear dependent.
You can go a very long time without extreme upgrades in your gear and still do quite well, and that's a good thing.
You CAN be powerful alone, and of course you can kill something. But you are 10 times as powerful when your behind your allies.
The following heroes are some of the heroes suitable for the Support role:
For a full list of Supports, see: