Mounts and Saddle
MTG Mechanic
Saddle is an activated ability that can be activated only as a sorcery, meaning during your main phases while the stack is empty. To activate a saddle ability, tap untapped creatures you control (other than the Mount itself) with total power greater than or equal to the number after saddle. When that ability resolves, the creature becomes saddled until end of turn. What that means exactly varies from creature to creature. Many Mounts have a triggered ability that triggers whenever it attacks while saddled.