Larian Studios Forums Divinity: Original Sin 2 Divinity - Original Sin 2 - General New Player in need of Help - Origin Char and Class

Int boost magic damage and weapon that scales with int (It will says right on the weapon)

Necromancy, Pyro, etc, anything that are magic looking are all magic based. Polymorph however, is Str. You can look at the skill to see it.

Necromancy is the most useful one atm because it deals physical damage if your team has a lot of physical damager.

Then it's Hydro because of the heal and magic shield to cleanse elemental CC (like stunned)
Then it's Geo because of the slow and if you're an undead, you will need to use it (or mix poison drink) to heal yourself.

You can pick up and learn any school of skill as you level up. Have a look at the GM mode first to figure out what skill you might come to love and take note of how many points into the skill tree will you need to learn them from the books. (Like Teleport requires Aero 2) The easy rule to remember that each level is equal to a Tier (so Aero 1 is a Tier 1 spell and so on) and your don't get to buy the next tier until you're at least 4 level up (so Tier 1 can be purchased at level 1 and tier 2 will unlock at level 4 and so on.)

So if you really want to play a damage team, I suggest 2 mages and 1 Battlemage wielding a staff. Using a staff make the melee skill scale with int so they can all help each other with magic damage.