Agrus Kos, Eternal Soldier

The original Agrus Kos was a Boros beatstick built to punish the color pie; this incarnation converts his signature into a targeting multiplier. The trigger is narrower than it first reads: it fires only when an ability targets him and nothing but him, and it fires for you, letting you pay to fan that ability out across your other creatures. Spells do not count, which quietly walls off the obvious pump-a-creature line and points you instead toward activated abilities that live on your own permanents: equipment activations, ping effects, tap-down and untap abilities, anything that puts a single-target instance on the stack aimed at exactly one creature. Each copy finds a fresh legal creature you control, so a wide board turns one activation into a full team's worth. The "targets only it" condition is what shapes the whole engine: the multiplier reads the ability currently on the stack, so an activation that split its targeting across several creatures never qualifies, but a flexible ability that happened to choose Agrus Kos alone (an Equip pointed at him, say) copies onto everyone else just fine. That condition is checked at the moment of targeting, not by what the ability could theoretically have done. The vigilance and the durable 3/4 frame matter less than the redirection he enables: he asks you to assemble a stable of one-target activations and treat them as anthems the instant they aim at him.