Deadpool is linked to unique combos( brain freeze, teachers pet, hailstorm etc), it takes 10 unique combos to get the mode ready for the first time. It takes more combos to get the mode ready again.
Deadpool will help defeat those pesky villains quicker and with more points which will help in getting all the villains completed to get to Dark Phoenix wizard mode.
Once the 10 combos or whatever is required is complete the mode is ready and the 4 dome flashers on the ramps will pulse.