I've done some pelegarth bloodmask mobs, but that was before I had brutes. I have not tried the both together much yet, and my shadowveils are in the paint queue.
. That said, I can offer more bloodmask-specific thoughts.
With a C deploy, the bloodmasks can quickly get in advanced positions to score or contest Motivations. It's very hard to not take Elsis Tagil with a pelegarth mob because she can use her Inspire for early combined activations to really rocket you upfield in force. With Evasion and Shield Guard, blookmasks are a great tarpit. Elsis's training can enhance this with plus Evasion if you tie up multiple models. Shield bash and the Howl's Inspire can help you do that too. I have not really tried a Warden with bloodmasks yet, but she can definitely help up their offensive output, where they tend to lack. Plus brutes add to that hitting power and durability, plus positioning manipulation. Chain Pull and Shield Bash can help you maximize either Elsis's or the warden's training.
I do like to pair Elsis with the Bloodchild. Fierce Resolve and Rally Point combo to really help you score Unstoppable Force or Call to Glory. Add a longhorn or two, and Escort Civilians is also a strong Motivation. And the natural durability of a bloodmask mob, plus their speed, means Burn it Down and Stand Your Ground are also very achievable. Really, the right build offers alot of tactical flexibility.
It might be interesting to try the following, based on a list I like but swapping out longhorns for shadowveils.
Elsis
Howl
18 bloodmasks
Bloodchild
2 shadowveils.