anything with restore fatigue in strengthens bloom effects
anything with restore magika adds contrast and strengthens colours
anything with damage health makes the screen throb slightly darker
anything with ENOUGH chameleon in will blur everything
anything with damage fatigue in will make sounds lower pitched and increase motion blur
but the magnitude of the special effects depend on the magnitude of the effects. the strength of opposing effects . also a better potion for helping made by someone with higher skill will have less special effects that disbenefit the player, whilst a better made poison will have bigger special effects.
but the special effects should not be enough to anger someone (like a crippled head in fallout) (maybe a blind spell might annoy the player) but instead make things more alive (and the player less reliant on hud)