Benzir, Vicious Archdruid

Creature spells you cast with a higher converted mana cost than among all creatures on the battlefield cost {2} less to cast.
As long you control one or more creatures with the highest converted mana cost or are tied for having the highest converted mana cost, each of those creatures have infect. (Those creatures deal damage to creatures in the form of -1/-1 counters and
to players in the form of poison counters.)