Archaeomancer

The body is just a vessel for the trigger: a 1/2 that exists to hand a spell back. What makes it the recursion engine of choice for blue's casual decks is that the trigger lives on a creature, not a sorcery, and creatures can be picked up and replayed. Pair it with anything that bounces or blinks a creature (a recurring flicker effect, a cheap return-to-hand spell, a sacrifice-and-recur loop) and the same instant or sorcery comes back every turn. The cleanest loop puts a two-mana removal spell or a bounce spell on a leash: cast it, blink Archaeomancer to retrieve it, repeat until the board is empty. Earlier graveyard recursion in blue tended to be one-shot card-advantage spells weighed down by buyback restrictions or steep mana costs; putting the effect on a fragile, easily-rebuyable body changes the math entirely, because the cost of looping it becomes the cost of moving a creature, not casting a four-mana spell each time. The 1/2 is what keeps the loop honest: it dies to almost anything, so the engine only runs if you protect it or if your blink outpaces their removal. This is the workhorse blue has reached for ever since, the part that turns a pile of cheap interaction into a soft lock without asking for a dedicated combo.