More info
Blue
Uncommon
Casting Cost - 3UU,
Non-Foil
Creature - Octopus [5/5]
Sealock Monster can't attack unless defending player controls an Island. {5}{U}{U}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.) When Sealock Monster becomes monstrous, target land becomes an Island in addition to its other types.
Illus. Adam Paquette