Ixalan

Siren's Ruse | Instant | | Exile target creature you control, then return that card to the battlefield under its owner's control. If a Pirate was exiled this way, draw a card. | Ben Maier

Costly Plunder | Instant | | As an additional cost to cast this spell, sacrifice an artifact or creature. Draw two cards. | Ben Maier

Sure Strike | Instant | | Target creature gets +3/+0 and gains first strike until end of turn. | Izzy

Pounce | Instant | | Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.) | Lucas Graciano

River Heralds' Boon | Instant | | Put a +1/+1 counter on target creature and a +1/+1 counter on up to one target Merfolk. | Alex Konstad