Merrow Skyswimmer

The two hybrid pips are the interesting part of the cost, because convoke can pay them with any Merfolk you tap that is white or blue: since the tribe lives in exactly those two colors, a wide Merfolk board covers the whole cost, hybrid pips included. That is the loop this card is built around. Cast at full price it is a 5-mana flyer with vigilance that leaves a 1/1 Merfolk behind, a reasonable go-wide finisher. But convoke turns a full board into a discount, and the enters-the-battlefield token pays part of that discount back, so a turn that would normally strip your attackers to power the spell instead nets you a fresh body. Vigilance closes the design: the flyer you just cast is not forced to choose between the swing and the crackback, so committing it does not leave your board open the following turn. None of the individual pieces is new. Flying-vigilance Merfolk and convoke-with-a-token both have long pedigrees. The craft is in how they lean on each other: a wide board makes the spell cheap, its arrival feeds the board back, and the resulting flyer stays useful whether you are pushing damage or holding the line. A deck committed to going wide gets a discount, a replacement, and a payoff that works on both halves of the turn, all wired into one card.