Whenever a creature you control deals combat damage to a player, draw a card if that creature has a +1/+1 counter on it. If it doesn't, put a +1/+1 counter on it.
Marcus rewards connecting with creatures: hit a player with a counterless creature to grow it, then every subsequent hit with a counter-bearing creature draws a card. Build a wide or evasive board, stick counters everywhere, and snowball into a massive card advantage engine that overwhelms the table. You win through trampling beaters, evasive swarms, or counter-multiplier blowouts.
Generates explosive card advantage in green, a color that traditionally struggles to draw
Synergizes with the entire +1/+1 counter package already strong in GU
Self-sufficient: even a single unblocked creature buffs itself and snowballs
Vigilance and trample on the commander make it a real threat that defends while attacking
Reliant on combat connecting — board wipes and Fog effects shut off the engine
Needs creatures to already be unblocked, so chump blocks and deathtouch slow it down
No built-in protection; removal on Marcus stalls the card draw
Can be grindy against fast combo decks that ignore the board
Legendary Creature — Mutant Advisor
