Tanking Question on Ignis

[Amenti]

My guild is a small guild just friends on a crappy server so not much people to ask questions to. I used to be on Ner'zhul and Raided with DBSS. We were doing attempts on ignis last night and our tank was getting hit for melee of upwards of 40k+. And only had 2 constructs active, we were using a DK tank with about 43k hp. Is that not enough? Should she stack all stam gems? Her name is Taktank. Please any suggestions would greatly be appreciated. Grats on your US first.