This is nice- I love any deck that makes use of ordinarily junk spells like
Crypt Rats that just need the right mechanic to make them superstars. And using them with
enrage creatures and
Brash Taunter creatures is great and fun synergy (side note: especially with the
indestructibility instants, I think
Blasphemous Act would be great to add. It combos fantastically with your
Brash Taunter creatures, and might be needed for some genuine removal. And in this deck it could potentially end the game if you also had Kaldheim's
Toralf, God of Fury). It might be worth considering
lifelink through auras/equipment/
lifelink counters that could go on
Crypt Rats or Kazarov or
Brash Taunter. Also, if you're willing to go big on card advantage with something like
Phyrexian Arena, I personally feel like it might be worth going even a little bigger with
Necropotence, or possibly scaling back to something like
Underworld Connections.
In these trying times my only real concern is Kazarov's safety. I know you have some interaction for it, but at 7 mana, it takes a lot of ramp to get him out the first time, and there's a lot of potential for hate on him by then. Did you consider any cheap reusable protection for him like
Ring of Xathrid or
Skeletal Grimace? Or
Whispersilk Cloak, which gives protection and also guarantees that you can swing with him.
Dust Corona is a great cheap one for penetration as well.
Great idea, great deck.