- Adding an entropy nymph is a fine idea, but remember it won't stand much chance out on the field without Quintessence vs alot of gods. This is what makes AM itself more effective in some cases. Adding quintessences would indeed imbalance the deck. (starting hands with 2-3 quints, no creatures etc)
- Adding time nymphs seems like a worse idea to me. It has the same problem of not surviving without a quint, but it's also more expensive then an hourglass. You generally want to use your hourglasses as quickly as possible in a match to set up your defense and offense, after that you just use them as PC-magnets. Time Nymph would be to slow.
- The best nymph to add to CCYB in my opinion is the Air Nymph. You could replace the FFQ with one. It would make fractal less usefull but generally the damage caused by Air Nymphs and it's UG's is a nice addition.
Sadly I don't own an Air Nymph.... :p