Nimrod the Wise

Haste.
As long as Nimrod is in play, you will not get
mana burn. Leftover mana in your mana pool
will be carried over into the next turn.
{x}{t}: Add {x} mana of any 1 color into your mana
pool.
{u/b}{b/r}{3}: Killing Cloud. Put a -3/-3 counter on
all creatures target opponent controls.
"Nimrod's mind has more knowledge than Geffen's
library."
-Ymir, Geffen's Scholar-