180 cards
Grixis

The main themes are flash, control, madness, artifacts, prowess, and wizards

U control

B midrange, graveyard

R aggro/burn

UB discard, reanimator, control, mill, flash

BR aggro, sacrifice, fast reanimator, madness

RU spells, wizards, tempo, flash, artifacts, combo, draw 2

UBr discard

BRu madness

RUb wizards

UBR

?? storm

With grid draft each card should probably either fit in multiple archetypes or really enable one

180 cards

20-24 lands

Remember that all madness cards can be played at instant speed for flash synergy