At the beginning of combat on your turn, put a number of +1/+1 counters equal to Maester Seymour's power on another target creature you control. : Monstrosity X, where X is the number of counters among creatures you control. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
Not legal in Standard, Pioneer, Modern, Pauper, Historic, Timeless, Alchemy, Brawl, Standard Brawl, Pauper Commander, Gladiator, Premodern, Pre-EDH, Old School, Penny Dreadful
Notes & Rules Information
The value of X is determined only once, as Maester Seymour's last ability resolves.
(2025-06-06)
If Maester Seymour is no longer on the battlefield when its first ability resolves, use its power as it last existed on the battlefield to determine how many +1/+1 counters to put on the target creature.
(2025-06-06)
Monstrous isn't an ability that a creature has. It's just something true about that creature. If the creature stops being a creature or loses its abilities, it will continue to be monstrous.
(2025-06-06)
Once a creature becomes monstrous, it can't become monstrous again. If the creature is already monstrous when the monstrosity ability resolves, nothing happens.