Lucian, The Purifier

First strike
Whenever a creature you control dies, put a vengeance counter on Lucian. If that creature's
name was Senna, Sentinel of Light, put four vengeance counters on Lucian instead. Then, if
there are four or more vengeance counters on
Lucian, transform him.
"I'll be alright, Senna, long as I've got you."