Let's compile one here.
Everyone post the ones they know about! (I am posting without double checking. If I made a mistake please point it out.)
Here are a few:
Fire + Water = Steam.
Fire + Poison = Explosion.
Fire + Oil = Bigger explosion.
Air + Water = Electrified water.
Air + Blood = Electrified blood.
Air + Steam = Thunder cloud.
(The above three conduct electricity through each other.)
Might post more after some experimentation.
Great list!
Is there any difference in the effect or damage depending on how the electrified effect is applied in those 3 instances?
Also, does the bigger explosion from Fire+Oil cause more damage than Fire+Poison?
