Broodwar: Defiler Plague counterplay
Setting aside the heresy of suggesting any change to Broodwar here's a little idea for increasing counterplay for the other races when dealing with late game Plague.
Terran:
Irradiate can now cure plague.
Creates hilarious scenario where the cure is sometimes worse than the disease.
Irradiate can only pause DPS upon mechanical units under it's effect. This is to address precasting irradiate on mass BC or Mech.
Fun factor: Actually having a reasonable, on hand answer to plague would be cool, if only to somewhat mitigate damage in exchange for APM.
Also having your plague cured by an irradiated Ultralisk hug would be peak comedy.
Protoss:
Plague no longer bypasses energy shields.
Spores remain active upon the unit for the duration of the spell but DPS only starts once shielding has been lost. Regenerating shields do not interupt DPS once infected.
This changes how plague is used in PvZ specifically, encouraging it to be correctly cast in the heat of battle.
Fun factor: feeling like a hyper advanced civilisation that actually has competant biohazard protocols.