Sylas immediately eliminated several things.
Using <Arctic King's Domain> would be foolish. They would just end up dying to the poison in a few seconds. The attacking spells were a decent option because the Arctic Emperor Cobra had never had great attacking ability. They would only do 100-200 Damage a piece, and so long as he controlled them well, it might be fine…
But the problem with that approach was that the Damage of the Arctic Emperor Cobra wouldn't stop there. He had even made it far too strong. The residual Ice-Poison effect would accumulate after the fact. So unless he used Rune Soul to expel the attack every time, they would eventually die to accumulated Damage as well.
Sylas hadn't thought that he would ever run into a problem where his cards were too powerful for the situation, but here he was. If he was careless, he could ruin everything.