Scuttling Sentinel
A protection spell disguised as a body. The 3/2 carries a trigger, and flash is what makes that trigger dangerous: hold three mana, let an opponent commit removal to your best threat, and drop this in response to put a +1/+1 counter on that creature and wrap it in hexproof through end of turn. The target dodges the spell and grows in the same window. Its own vigilance is almost incidental here, more a keyword that matters on later turns when the Sentinel itself starts attacking than anything relevant to the trigger, which touches a different creature entirely. The hybrid cost is a quiet convenience: either half of a Simic shell can cast it without both colors online, which extends its reach more than the modest body ever could. The blue-Crab typecheck is mostly flavor freight, though not nothing, since any effect keyed to Crabs or blue creatures gains a member for a turn. The distinction worth drawing is about what survives the turn: the hexproof and the added type revert at cleanup, but the counter stays. You are paying a card and three mana for a protected growth spurt delivered at the exact instant an opponent spends mana to kill something, a narrower and sharper job than a plain two-for-one.
