Being able to Proliferate multiple times on the same turn, Inexorable Tide will allow you to give your Creatures huge buffs or take your opponents out of the game in one fell swoop
Whenever chaos ensues, for each opponent, choose up to one target nonland permanent that opponent controls
Secret Tunnel looks like a direct replacement for Rogue's Passage, but hold on there, tiger
Honorable Mention Hashaton, Scarab's Fist Let's start with this two-drop blocking 1/3 size guy for Orzhov mana, and then when you discard that dork you can spend three mana one of which is Blue to make a tapped token copy of it at 4/4 size and a Zombie too
This could be the card that makes Improvise strong, as in Delve strong, but not quite, because Delve did not need much enabling