The Cave Surveyors

Begin the game with this card revealed.
Only creatures your graveyard gain
Unearth {2}{p/b}{p/b}, and Dredge 3.
When a creature you control is exiled due
to Unearth, investigate.
If you have 12 or more creatures exiled due
to Unearth, create a 12/12 black and green
Lizard token with riot, reach and Annihilator 2.
The token cannot attack unless it is the only
creature you control.