Rushmore challenge tactics

[junta74]

I have been soloing Moving Targets and finally get all the ingredients I need. I have to do Picture Portals next so i went to the forums for some ideas on the elementals because the "rush the boss with everything I got" doesn't seem like the best idea. From some developer posts, they hinted at a different way to do it, but couldn't find any ideas. Has anyone found a tactic for these fights?

[Shade]

Rush the boss with everything you got is indeed the correct approach. What do the devs know?

Picture portals u can bribe the kobold to give u quad dmg too, that really crushes the bosses.

[Deathdefy]

If you literally cannot beat his regen, then you'll need to kill off elementals until the types of elemental left do not include water.