As removal, The Wandering Emperor is a bit overcosted at four mana, but exiling any tapped creature (and gaining some life as a bonus) is solid, especially if we flash it into play during our opponent's turn
All Shall Smolder in my Wake AND Tooth, Claw, and Tail These are two of the best answers and removal in Scheme form
Katilda, Dawnhart Martyr and Lier, Disciple of the Drowned from Innistrad: Midnight Hunt
Edge of Eternities is Magic: The Gathering's first foray into space (in a canon set, anyway)
In the previous article ranking the top blue cards in Modern, I talked about how the big difference between Modern and Legacy historically has been the lack of universal answers in the former, while the latter has cards like Daze, Force of Will and Wasteland
Double-faced cards : They state that selecting a DFC automatically prints both sides (so youre not juggling two separate cards)