Verb: To "tank", or "tanking", would be the action of performing the duties of the tank as described above.
2.V. The warrior is tanking the mob right now.
3.V. Do you think you can tank this mob for us?
Guy 3: Im gonna get you!
Guy 2: Don't worry that bastard is on lock down.
Guy 3: God Damnit!!
Guy 1&2: TANK!!!
"That car is a tank. Its been flipped 4 times, hit a guardrail, a deer, and a fencepost! And I drive it everyday..."