Eidolon of Countless Battles (SOC-144) [Commander: Secrets of Strixhaven]

Bestow 2WW (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.)

This creature and enchanted creature each get +1/+1 for each creature you control and +1/+1 for each Aura you control.