I did a WG with it last night and 5 of those will eat through a siege tank rather quickly. Where it really proved to be useful was melee swarming in. Pop 5 magma totems and channel 5 earthquakes on top of yourself and the knockdown/damage is very effective against them. And yes, seeing them crit for 2.5k+ definitely gives potentional.

I really wanna try EOTS and put them at the end of one of the chokepoints on a bridge