It might be an idea but the point of dummies is you can hit them forever and they will never die. However, your dilemma you can still do it without a dummy, as long as you don't hit that specific mob.
It's an intricate thing you are asking for, problems will arise like:
1. how would you calculate your dodge chance on a level 1 dummy for example (higher level players dodge more often on lower level mobs). Can maybe scale the dummy to the player's level, but more problems/in depth coding needed.
2. if somehow these dummies were made to attack, to scale, multiple players won't be able to use it.
3. err, too sleepy, can't think of more

Anywho, not totally abandoning the idea though, might see it, maybe...