Increment is a creature ability that triggers when you cast a spell and spend more mana on it than the increment creature's power or toughness. If the comparison still works when the ability resolves, that creature receives a +1/+1 counter.
Fractal Tender turns successful counter growth into Fractal tokens, while Tester of the Tangential can redistribute its accumulated +1/+1 counters. Increment naturally encourages progressively larger spells as its creatures grow.
