-sigh- Commanders emphasis on color identity in deckbuilding has successfully kept Krrik, Son of Yawgmoth from being a huge problem in the format as a whole, but its still a powerhouse that should be removed or countered on sight against decks with a large or exclusive emphasis on black, as 4 mana can easily become as much as 16, more if life gain enters the equation
The other Gearhulk cards are also pretty valuable out of the gate: Riptide Gearhulk and Oildeep Gearhulk are also in the $9-$10 range
Life Drain Whenever a creature dealt damage by this creature this turn dies, create a tapped 2/2 black Zombie creature token and exile that card
In decks like Voltron or Bogles, this is incredible
Otherwise, its mechanically identical to the original version of the card
Sarkhan, Soul Aflame is a dragon decks best shapeshifter, making your dragons cheaper and copying the newest one that hits the battlefield, which leads to some pretty wild double-threat turns