One thing that could be a interesting feature would be an dissipating enchantment with a ongoing counter effect (mind) and which generates a large bonus (dark) when it is destroyed by the end of the count down. Something like this:
Dark soul.
Cost: 2+3
Effect: Dissipate 2. Upkeep 1. When target creature, or any of its attached objects, is affected by an opponent spell that opponent must pay 2 additional mana. When Dark soul is destroyed by the dissipating effect it gives it's creature +3 melee, +3 range, and full attacks becomes quick attacks until end of round.
In this way the opponent have a choice to dispell before the enchantment takes effect.