Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.) : Add . Target opponent gains control of this creature. (Activate only as an instant.)
Legalities
Not Legal
Alchemy
Brawl
Explorer
Future
Gladiator
Historic
Modern
Oldschool
Pauper
Paupercommander
Penny
Pioneer
Standard
Standardbrawl
Timeless
Legal
Commander
Duel
Legacy
Oathbreaker
Predh
Premodern
Vintage
Rulings
2008-04-01
Because the ability is targeted, it is not a mana ability. It can only be activated when you have priority, and goes on the stack like other non-mana abilities.