Its intended to be a permanent effect. It would work with a low/or no creature deck, causing their creatures to kill each other. But, on the flip side, it could also hit you. Its just pure chaos, something that could change what a druid creates/intends big time. I figured the infection part would likely ensure that its not a long lived effect. But, of all existing cards and concepts, I believe that "confusion" could cause the most chaos. Even the one putting it in play is at risk, like you said, a properly built deck would ensure some safety from your strategy.