Doctor Strange: Can I resolve Images of Ikonn if the villain is already confused and there is no threat on a scheme?

Yes. As long as any part of the ability on Images of Ikonn can change the game state, then it will do as many effects as it is able. While its first effect may fail to change the game state if the villain is already confused and there is no threat on a scheme, its second effect can change the game state by placing itself in the Invocation deck discard pile.