I feel like if we're going with the kiss/curse design with regard to pact of consume, the healing reduction should ramp up over time rather than immediately turning me into a coughing baby that can't receive healing until monsters & memories 2 comes out.
Why can't we instead "ramp up" to the (hilariously overtuned) target number of 85%? Each cast of pact of consume could incur an additional healing reduction penalty, but if we don't cast it for 12/24/36 seconds or whatever then allow the healing reduction to drop off completely.
It prevents consuming endlessly to have an "infinite mana bar" because eventually you're going to be unhealable (could you imagine?) but allows managing risk vs reward in a way that's actually engaging and driven by player agency rather than outright debilitating. An 8 second cooldown is already taxing in terms of action economy, and allows for this to get going in the wrong direction VERY easily.
You could even use this "sickness" as a way to empower our offensive abilities, similar to druid seasons. Maybe after I consume x times my offensive spells are increased in potency for the duration of the sickness to give you another decision to make. "I've been spamming consume to get mana back, and I can spend some of that mana to deal substantial damage over the next 30/60 seconds, but if I continue to spend mana, I'll have to consume again, and I'll be unable to heal myself if I draw aggro with that damage"
To me it feels like the 2 minute debuff duration is simply a way to lock us into using a single consume spell, which I am all for, but it's limiting consuming pact from being as described above which would be actually good and fun to use rather than, "I am not sure I should ever fucking use this."