What offensive moves can Amadeus (the Wizard) use?

You have if I remember correctly 2 solutions :

• Learn the skill to levitate ennemies and use it to throw them away.
• As in the first Trine, create an object and let it fall on your ennemies from a good height. (You can use environnement items such as rocks aswell)

Remember that in general, anything that can harm you can also harm the enemy. With that in mind, at the start of the game with no upgrades, Amadeus can

• Create or drop objects from height. This takes a bit of timing as gravity in the world of Trine seems to be rather sluggish
• Redirect environmental hazards at the enemy. You can point those fireball spitting flowers by grabbing them and pointing them at the enemy, light explosive barrels on fire then fling them towards the enemy, or throw spiky balls at them

Once you obtain the level 1 monster levitation upgrade (a very useful upgrade), you can

• Drop monsters onto spikes, pits, poisonous gas, acid, flames, and any environmental hazards you can find
• Use monsters as meat shields. The AI is extremely stupid, and will continue to shoot at you even when their compatriot is in the way.

There are achievements for doing both of the above. Dropping the enemies themselves from height only seems to stun, not damage them. As always, there's plenty of room for creativity when it comes to playing the wizard.

Do remember when engaging enemies that you cannot move while engaging your magic, and though enemies are stunned during and for a short while after you grab them, you can still be attacked from the back.