Legendary Creature - Human Assassin Mari, the Killing Quill Whenever a creature an opponent controls dies, exile it with a hit counter on it
The combination of useful upfront from the five life it gives you and the ability to generate advantage over time is actually kind of a nice package, particularly if you can play a single copy (whether maindeck or sideboard) to tutor up with Priest of the Wakening Sun or look for with Commune with Dinosaurs
Like Frantic Search, Snap can even be mana-positive if you happen to have effects that discount a spell's cost like Baral, Chief of Compliance
Each card in the Inkwell is worth just one Ink, and players are able to Exert (turn sideways) as many cards in the Inkwell as necessary to pay Ink costs
Defiler of Instinct Of all the Defilers, Defiler of Instinct hurts the most from the permanents-only restriction
Additional support cards like Erratic Portaling it in response or utilizing Homeward Path is a big help, but they're often narrow in their applications, making Starke of Rath an extremely cool design that's bad in the sense that it'll rarely end up working out in your favor