Obelisk of Turd

Revoke (Your creatures can prevent the casting of
this spell. Each creature you tap while casting this
spell increases the cost by {1} or one mana of that
creature's color.)
As Obelisk of Turd enters the battlefield, choose
a creature type.
Creatures you control of the chosen type get
-2/-2 and cannot attack or block.
"Tell me again why we sought out this magical relic?"