MTGNexus

Bit of a basic question here but I thought I'd get the wording confirmed..

So Mind Harness says it can only be used to enchant a red or green creature. If a creature has one of those colours, but also has others (golgari, sultai, 5 color etc), is it a valid target? Or is it not "only" a red or green creature? Thus this aura can only go after Gruul?

No, colors are additive. A creature that is red and another color does not become not red. "Enchant red or green creature" means you have to enchant something that fits at least ONE of those conditions (red creature and/or green creature). The card can target and be attached to monored, monogreen, red-white, green-blue, five-colored, etc. creatures.

nice one thanks, there were just some comments about "how colour restricted it is" which made me second guess it. Depends on the meta the person has chosen it for I suppose.