Ghoulfiends and Entire Combat conflict?

[Trypto]

My friends and I were playing and I was in the middle of combat. I was fighting a Amazon when they wander in the Ghoulfiends and like 2 other monsters. I charmed the ghoulfiends since I can only fight with my level. I thought that restriction would be gone since when you charm a monster it says that it is now discarded. Well they started quoting the rulebook saying that if a monster has any special ability that it applies to the ENTIRE combat. Does that effect stay active even though the Ghoulfiends are gone because it is the same combat?

[DoomedDuck]

Once a monster is removed from combat, its special abilities no longer count either.

[six's monkey]

Think of special abilities as working combat-wide in space but not necessarily in time?

[MunchkinMan]

If a Monster is no longer involved during a combat, it's special abilities are no longer part of the combat.