pokemon card neo japanese set Darkness, and to Light... Booster Pack Neo Starter Deck (TCG) -

Both Shard Phoenix and Spike Feeder can be sacrificed for zero mana, meaning Bob could actually keep Oathing turn after turn, thanks to the aforementioned Gaeas Blessing recursion keeping things going

8: Search your library for any number of Dragon creature cards, put them onto the battlefield, then shuffle

If you choose to sacrifice another creature, a second triggered ability (called a "reflexive" triggered ability) goes on the stack and you choose a target nonland permanent at that time

Add to it that you can play removal in a mono-blue deck and you get a hell of a card

Path of Exile and Swords to Plowshares are there are instant-speed answers, but they seem insufficient to delay the armies of players that don't want to stare down a Silent Arbiter

I like the card Augur of Bolas, but you kind of have to warp your deck design around playing that card