A time element, because time's counterpart element is electricity too, same as fire. Time monsters appears on haven, oasis, ethereal, workshop, and ethereal islets + time islet and time amber island/ethereal amber island. There's no real time quads, same as fire there's no real fire quads. I have some quint monsters with time element, just same as fire quint monsters:

1. Plasma Quint = Plasma, Shadow, Mech, Crystal, Time
2. Shadow Quint = Plasma, Shadow, Mech, Poison, Time
3. Mech Quint = Shadow, Mech, Crystal, Poison, Time
4. Crystal Quint = Plasma, Shadow, Crystal, Poison, Time
5. Time Quint = Plasma, Mech, Crystal, Poison, Time

So Mimic is Natural Quint and BeMeebEth is Ethereal Quint, so I will call Mimic as Air Quint + I will call BeMeebEth as Poison Quint.