Duration of the winter event

[Zaospeed]

Hey guys
The winter event is awesome and all but some of us (including me) have exams at the moment. Does anyone know untill which day we can kill bosses? Would be easier for me to guess how much energy i'll need to buy. Thanks in advance

[Otahaanak]

Pretty sure that someone already figured about 130 runs or less (if you get higher tiers to take you through) based on their experience on the test server.