Uh...

to make sure you do not get hit by the ice shards coming out of the ground.. do a Dodge Roll over and over to avoid...

The dogde roll is given for you for that reason!
Every single one of the bosses (cept Ursela) in that game has some kind of attack where an attack comes out from under your feet.

Anyway, hit a couple ice shards back...

blast him with magic...

cure

smack some shards

blast him with a spell

cure..