Rework Idol of Yogg-Saron to make Shadowy Apparitions explode on contact, dealing a portion of their damage to nearby targets.
Limit the damage portion (maybe 15%) and the targets affected (up to 5) as needed.
Rework Mental Decay to cause Shadowy Apparitions to extend dot duration on contact. This makes it useful for both single target and AOE as a passive dot increase which allows more focus on rotational spells and less on reapplying dots which then allow dot application from spells like Shadow Crash to be more effective with larger groups since your dots being extended via Mental Decay would cause less overlap issues.
Rework Idol of Y’Sharrj to either buff/enhance your damaging Mind Spells uniquely like Mind Flay can be used while moving or Mind Sear reintroduced and it can spawn Shadow Apparitions when it deals damage while Mind Bender is active or just flat out buff all damaging Mind Spells by a noticable amount while Mind Bender is active.