Black Mage

[Kabooa]

TL;DR: Make Scathe, Freeze and Blizzard II killy, and replace Sleep with a self buff.

I don't see those changes affecting the current status of Freeze and Blizzard 2.

For those two, I'd suggest this.

Blizzard 2: Enemies hit by this spell are inflicted with Shatter. They will take additional damage from the first Damaging spell that hits them, at a reduced rate when that spell is an ally's.

Freeze: Turned into an ability.
Duration: 15 seconds
Cooldown: 60 seconds
Radius: 10y
Effect: Enemies within the area effect are afflicted with Heavy and Shatter for as long as they remain inside.

Black Mages gain a Caster friendly boost as well as a personal damage increase. Blizzard 2 and Freeze both gain a definitive spot in the spell arsenal.