On paper, Dissipation as a healing CD isn't bad. Consider the following:
  • Fairy Embrace is approximately 200 Potency every three seconds. Over the course of the 30s cooldown, you've lost 2,000 potency.
  • Three AF charges will give you back 1,800 potency on Lustrate (2,000 if you use one charge on Indomitability in a two tank scenario). You've now made up or close to made up the amount of healing lost with the use of Dissipation.
  • In the case of using all three charges are for Lustrate, you'll need an additional 3 Physicks to make up the remaining lost Potency from Fairy loss. Anything beyond these three Pysicks is icing on the healing cake.

Effectively what Dissipation does is front load a SCH's healing. Unfortunately, this is marred by two scenarios:
  • The cost to resummon the Fairy requires 1,768 MP and generally Swiftcast to reduce downtime.
  • There aren't enough scenarios in the game where a SCH needs to front load that much healing for that kind of duration. The only scenario I can think of is at the beginning of Wave 9 in A2S where ALL THE DAMAGE is going out at once for a prolonged period of time.

The MP cost to resummon the fairy is worth four Physicks and the only way a 20% healing buff makes up for that is if you Physick 20 times in those 30 seconds which is impossible to do, let alone the fact that you shouldn't need to be constantly healing for the entire duration of the buff. There's also the non-measurable cost of consuming your Swiftcast to resummon said Fairy quickly.

Just on the vein of "how to fix", I was just thinking that it would be neat if every time you use an AF stack for healing purposes (Lustrate, Indomitability, Sacred Soil) while Dissipation was active, it would provide a stacking buff that caps at three that reduces the cost of the Fairy resummon by 25% and cast time by 33% that lasts for 45 seconds. Maybe a little too wild but I liked the thought in my head. lol.