Using two or more abilities at the same time

[Fufu]

Munchkin Pathfinder combo: Ally "Valeros," "Necromancer," "Red Mantis Assassin," and "Super Munchkin."

• Does this Munchkin Pathfinder combo allow the player to stack their abilities, which are triggered at the same time or does the player have to choose which ability they are using?

"Super Munchkin" or "Double Life" gives the player the ability to be multiple classes / factions.

• Does this allow the player to stack their abilities, which are triggered at the same time or does the player have to choose which ability they are using?
• For example, if the player is two "Necromancer" classes, can the player use both the "Necormancer" class abilities at the same time?