Most played cards in Grixis Aggro:

2 Decks
Brainstorm
8 copies - 4 average
Daze
8 copies - 4 average
Force of Will
8 copies - 4 average
Ponder
8 copies - 4 average
Delver of Secrets
8 copies - 4 average
Thoughtseize
7 copies - 3.5 average
Misty Rainforest
7 copies - 3.5 average
Wasteland
7 copies - 3.5 average
Watery Grave
4 copies - 2 average
Lightning Bolt
4 copies - 2 average
Polluted Delta
4 copies - 2 average
Fatal Push
4 copies - 2 average
Underground Sea
4 copies - 2 average
Death's Shadow
4 copies - 2 average
Gurmag Angler
4 copies - 2 average
Street Wraith
4 copies - 2 average
Preordain
3 copies - 1.5 average
Surgical Extraction
3 copies - 1.5 average
Volcanic Island
3 copies - 1.5 average
Pyroblast
3 copies - 1.5 average