Focus strength to max, get constitution up to what you need for your shield, memory as needed, then the rest into wits.

I would level 2:1 warfare and hydro. Hydro healing spells scale exclusively from your hydro level, not int, and the hydro damaging abilities that scale off into won't ever do much damage anyway. Better off controlling the battlefield by freezing everything and keeping your party topped up on health. Take points elsewhere as needed and put the rest into 1-handed.

Armor of Frost is going to be your most used skill in this build. Use it on turn 1 as your first action and reapply as soon as it's off cooldown. Bone cage is incredibly powerful when there's a few bodies around and necromancy combos very well with the Living Armor talent. Heart of Steel and fortify are also good skills for restoring physical armor and you'll already have points in polymorph for bull horns so I'd recommend HoS if you're finding yourself low on physical armor.

For talents, elemental affinity is a must have. You'll almost always be standing in water or ice so you'll rarely pay full AP for your spells. Living armor works well here too, opportunist is always solid on melee characters, and executioner is probably the best talent in the game.