What it does
Myriad is an attack trigger found on certain creatures (mostly from Conspiracy and Commander sets). When a creature with myriad attacks, you create a token copy of it for each opponent other than the one (or planeswalker/battle) it's attacking, and each token attacks a different opponent. At end of combat, those tokens are exiled.
The big nuance: the tokens enter the battlefield already attacking, so they skip the "declare attackers" step—meaning attack triggers that say "whenever this attacks" will trigger off the tokens, but you don't choose to attack with them or pay attack costs again. Also, the tokens are exiled at end of combat regardless, so don't expect to keep them.
In Commander, myriad shines because you usually have three opponents, effectively tripling your attacker. It's fantastic with damage triggers, combat damage payoffs, and "whenever a creature you control attacks" effects, letting you spread pressure across the whole table at once.













