I provided plenty of insight on how diverse and how powerful Sinkhole can be
Vault 12: The Necropolis Wasteland Raider Acquired Mutation Assaultron Dominator Bottle-Cap Blast Crimson Caravaneer Duchess, Wayward Tavernkeep Grim Reaper's Sprint Ian the Reckless Junk Jet Megaton's Fate The Motherlode, Excavator Mysterious Stranger Plasma Caster Powder Ganger Rose, Cutthroat Raider Synth Eradicator Thrill-Kill Disciple Vault 21: House Gambit Veronica, Dissident Scribe Wild Wasteland
Hyena Umbra, meanwhile, is a piece of armor thats cheap to play and easy to recur, with a relevant keyword to boot
See you on the next one
Echo of Eons Echo of Eons can be potentially two Timetwisters in one, or at least one if you manage to discard it and flash it back
Make your creatures extra-hard to target and remove, and make your opponents' creatures fight on your behalf