I just did the math, and unless we can recover some Essence at the gate, we only have 184 motes between the four of us. One option I can see is if Karyn can summon a demon and order it to aid us in using its own Essence to fuel the remainder.
The problem is, the ritual to summon a demon is four hours long, culminating at midnight. The time it will take is also a problem, along with the end time requirement.
The problem is, the ritual to summon a demon is four hours long, culminating at midnight. The time it will take is also a problem, along with the end time requirement.