Need help with Bloodmage, Detonate Dead, please!

Hi Guys,

currently I'm running a Bloodmage build with Detonate Dead as main attack (3x Brutes, 4x Clerics).

My Brutes are very tanky (91k Life), so on normal maps witch Breaches, Rituals, Bosses etc. they rarly die, when I trigger Detonate Dead on them (I'm using "Sacrifice").

In contrast to that on Delirium maps the minions die instantly in the moment, I start using Detonate Dead. In addition to that the explosion of one Brute makes all other Minions also explode (because they are in the range of the explosion of the detonating Brute).

Does anybody know, what makes the Delirium maps so different, that the minions die so fast (instantly)?

P.S.: My minions have low restistences (ca. 30%). But this should not matter, because they are dying because of my Detonate Dead-Explosions and not because of the impact of the monsters. Or am I wrong?

Thanks very much!!!