The outcast text of the card was “This costs 0” and now it’s “This costs 1”.
With the nerf, the outcast text should read “Reduce the cost by 2”. It will get the same effect in reducing eye beam to 1 mana on outcast, but it wouldn’t make outcast worse with eyebeam if the card has been reduced by Skull of Guldan (or any other spell reduction effect that would bring the card to 0).
What happens right now is the card costs 0 with skull of guldan, or kaelthas on the third spell, but if it’s in the outcast position it will cost 1 instead of 0. That makes outcast a liability for eyebeam when the eye beam is already discounted to 0. This is absolutely an oversight.
I understand you just wanted to leave the text as is and change the number, but if you were designing this card over you would not have done “this cost (1)” but rather discounted it, for the obvious clash with skull of guldan.