Skeleton and mummy should be allowed for this event. While they do not have actives, their passives require time quanta. Ghost of the past should also be allowed, as well as nightmare and voodoo doll. I also think you should allow for one spell from each element: nightmare, plague, rage potion, basilisk blood, momentum, rewind, purify, mitosis, the mass dive air card, twin universe, mutation, and holy light. Said cards synergize well with other elements (in some cases they are counter-synergies).
Also, I have a feeling mind flayers will be a tad OP in this format... graboids could have been, but with the lack of earth/time creatures fit for rushing, a deck around them probably won't be too great.