That’s the point of Skills! To help you defeat Creeps!
2 of Frozone’s Skills (White and Blue) rely on Skill Level, that’s why it says “freeze may last for 1 or 2 seconds on enemies higher than (Skill Level)”.
Upgrade those Freezes so that the Enemies can’t attack, giving time for Yax’ and Frozone’s Green Skills (the main damagers) to charge up.
This might be my last advice for you, take it or leave it.