Turtle classes

Intriguing title, no? =)

For those of you who don't play many RTS games, there's a playstyle called turtling. Like a turtle, the player hides in his shell (plays defense) until finally summoning the energy to bite your finger (hit the enemy with the massive army he's been building). Basically, it means holding off the enemy long enough so you can crush them with overwhelming force.

I'm a turtle player. Honestly, it's not the most effective strategy, but it works well enough against computer AI.

But where it really shines is as a support strategy when allied with another player. My brother, my cousin and I play Battle for Middle Earth 2 cooperatively. Usually, we play with just two of us in the war mode, but we sometimes play skirmishes with all three of us, too.

RPG turtle power
I've already seen two examples in MMOs. In EQ2, a berserker inflicts more damage as he takes damage (or something like that; it's been a while). In WoW, a warrior gains bonus damage the longer he fights continuously. It looks like Tabula Rasa will employ a similar mechanic for all classes.

In what other interesting ways might this sort of playstyle be applied to RPG classes (or in general)?