At level 22-23 you'll face Belial. The battle takes place over3 phases. Within the first phase you'll just fight adds. Now I'll show you the diablo 3 wizard guide of belial regular. This will not be essential until the more tough difficulties although. If you're having issues with Belial, make sure you have some decent gear. My DPS was 144 base and 171 with Magic Weapon. I also had right about 1150 health. I used the following skills: Magic Missile, Arcane Orb (I could have used Ray of Frost for certain), Diamond Skin, Hydra (worthless here), Ice Armor and Magic Weapon. Within the second phase you'll fight Belial in human form along with exactly the same adds. He has a few attacks, all of that are avoidable by getting out of the way from the green zones around the ground or by sticking to the leading correct of the area to avoid his breath. Essentially just avoid the green locations, I grabbed Diamond Skin just in case they raining part was a problem. Arcane Orb, Wave of Force and Frost Nova would assist a great deal here. Around the third phase you fight Belial fin demon form. None of those were crucial, you can probably beat him with any random set of abilities. These are very easy but it is good to have Arcane Orb. I also grabbed Hydra rather of Wave of Force, which was dumb. The Hydra doesn't do sufficient damage to counter Wave of Force throughout the adds phase. I used Energy Hungry and Glass Gannon for extra harm and Arcane Power. Hope the the diablo wizard guide
of belial regular will probably be useful to you.