Shorecrasher Mimic

The fuel requirement is the whole point, and it is deliberately narrow: the trigger checks for a spell that is genuinely both green and blue, which a counterspell does not satisfy and a green ramp spell does not either. You need the intersection, the gold-or-hybrid Simic spell that lives in both colors at once, and that scarcity is exactly what keeps a recurring 5/3 from being free. The body sits at a fragile 2/1 until a qualifying cast sets its base power and toughness to 5/3 for the turn, which means the pump is a switch, not a counter: a second qualifying spell in the same turn rebuilds the same statline rather than adding to it. So this is not a card you stack; it is a card you turn on, ideally on a turn where the 5/3 connects. The trample clause is doing more than it appears, because a 5/3 a defender can chump is just tempo, while a 5/3 that runs over blockers converts a stalled board into a clock. It belongs to the lineage of aggressive guild-loyalty payoffs that price your color discipline as the activation cost: the reward only arrives once you have committed your spell base to a single two-color identity, which makes it an anchor for that pair rather than a splash. The Shapeshifter's shifting silhouette earns its type line by changing shape on cue.