Tidebinder Mage

In Commander, Tidebinder Mage is a role-player in blue tempo and Merfolk tribal decks — the tap effect answers green mana dorks and red haste threats that would otherwise outpace you, and it synergizes with Merfolk lords when you're running the tribe. In Modern and Legacy, it slots into Merfolk as a threat-plus-answer that pressures red and green aggro matchups, though dedicated removal or counter magic usually edges it out at higher power levels. Pioneer Merfolk lists will consider it for the same reasons, but the narrowness of the color restriction keeps it a sideboard option rather than a maindeck staple in most constructed formats.