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Monstrosity“Monstrosity N” means “If this permanent isn’t monstrous, put N +1/+1 counters on it and it becomes monstrous.”
Monstrous is a designation that has no rules meaning other than to act as a marker that the monstrosity action and other spells and abilities can identify. Only permanents can be or become monstrous. Once a permanent becomes monstrous, it stays monstrous until it leaves the battlefield. Monstrous is neither an ability nor part of the permanent’s copiable values.
If a permanent’s ability instructs a player to “monstrosity X,” other abilities of that permanent may also refer to X. The value of X in those abilities is equal to the value of X as that permanent became monstrous. (CR 701.37) 4. (If this creature isn't
monstrousA designation a permanent gains from monstrosity until it leaves the battlefield. (CR 701.37), put four +1/+1
countersTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on it and it becomes
monstrousA designation a permanent gains from monstrosity until it leaves the battlefield. (CR 701.37).)
As long as this creature is
monstrousA designation a permanent gains from monstrosity until it leaves the battlefield. (CR 701.37), it has
hexproofHexproof is a static ability.
“Hexproof” on a permanent means “This permanent can’t be the target of spells or abilities your opponents control.”
“Hexproof” on a player means “You can’t be the target of spells or abilities your opponents control.”
“Hexproof from [quality]” is a variant of the hexproof ability. “Hexproof from [quality]” on a permanent means “This permanent can’t be the target of [quality] spells your opponents control or abilities your opponents control from [quality] sources.” A “hexproof from [quality]” ability is a hexproof ability.
Any effect that causes an object to lose hexproof will cause an object to lose all “hexproof from [quality]” abilities. Any effect that allows a player to choose a creature with hexproof as a target as though it didn’t have hexproof will allow a player to choose a creature with a “hexproof from [quality]” ability. Any effect that looks for a card with hexproof will find a card with a “hexproof from [quality]” ability.
“Hexproof from [quality A] and from [quality B]” is shorthand for “hexproof from [quality A]” and “hexproof from [quality B]”; it behaves as two separate hexproof abilities.
“Hexproof from each [characteristic]” is shorthand for “hexproof from [quality A],” “hexproof from [quality B],” and so on for each possible quality the listed characteristic could have; it behaves as multiple separate hexproof abilities.
Multiple instances of the same hexproof ability on the same permanent or player are redundant. (CR 702.11). (It can't be the target of spells or abilities your opponents control.)