You suddenly appear in the middle of the battlefield, different enemies are approaching, and you know that the only way to survive is to survive.
Suddenly a package hits you, and then you get a new character to control, and you'll fight with a new character and new abilities.
You charge up your character's skills, and then you find that you can use explosive finishing skills. Faced with more and more monsters surrounding you, you know it's time to finish them off.