Kaalia of the Vast is unique in that it rewards playing with 3 tribes instead of just 1, and gives you a way to play the traditionally big, expensive Demons, Dragons, & Angels from your hand simply for attacking
Right now mono white and mono red decks dominate the standard meta in Magic: The Gathering , but that trend may very well change with the release of the Phyrexia: All Will Be One set
If youre already holding this when that Blasphemous Act goes off, you can even use it to reanimate your commander with two +1/+1 counters on it
There's an argument against essentially forcing players to carry around periphery items to track their cards correctly, but innovations like dungeons and ability counters already do this to some degree
Bloodghast still sees plenty of play in the Commander MTG format, but the card has long been an MTG Modern staple, too
Even though its been reprinted several times, be wary that it still commands a pretty high price