Blightbringer Regent

Flying, wither (This deals damage to creatures in
the form of -1/-1 counters.)
Whenever Blightbringer Regent deals damage to a player, they must discard a card. Exile the
discarded card, and until end of turn, you may
cast that card and you may spend mana as though
it were mana of any color to cast it.
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"The stuff of nightmares even among the Grixis."
-Eliza of the Keep