There are also cards that care about how many creatures in your graveyard, like [mtg_card]Bonehoard[/mtg_card]
However, I've picked out four that are up there as the best from my experience playing with Markov as a Commander
It has seen some constructed play, as the ability to dump mana into it is also just very strong
Not only can this improve the potency of already dangerous Dragons, but when paired with effects that provide additional combat steps, this ability may be triggered several times within a single turn
This means, for example, that you can't target two creatures and assign them two and zero counters respectively
Defiler of Instinct Of all the Defilers, Defiler of Instinct hurts the most from the permanents-only restriction