Idolized

Enchant creature
Enchanted creature has "Whenever this creature attacks alone, it gets +X/+X until end of turn, where X is the number of nonland permanents you control."

Renowned for your extensive support and goodwill, you are idolized by the community.

Fallout

A creature attacks alone if it’s the only creature declared as an attacker during the declare attackers step (including creatures controlled by your teammates, if applicable). For example, the ability granted by Idolized won’t trigger if you attack with multiple creatures and all but one of them are removed from combat. Similarly, creatures that enter the battlefield attacking later in combat won’t be considered when determining whether or not a creature attacked alone.