Hoarfrost Lich

Freeze on the opposing champ heals the frozen champ 4hp

 

It's supposed to. It Freeze = Crystallize you can use on the opponent. Read Crystallize's description.

 

ok still why would I intentionally freeze may opponent then heal him

 

It's similar to stun. Two turn CC, heals 4 hp, but the effect ends on your turn and it's not on the attack chain.