Which units would you replace in the Sylvan castle?

Alternatively, you could completely remove the beekeeping aspect from the Dryads or reduce the number of Druids and introduce a fairytale dragon, which is probably the cutest creature among all the units in the last three installments. Give it a random offensive spell, extremely low defense, and damage similar to that of a bone dragon. An upgraded dragon could also cast mass spells on its own units, but only for a short time, to maintain balance.