He's probably the hardest thing in Act 1 on normal difficulty, because he fights in a non standard way. Hopefully you have an Earth expert who can keep regeneration up.
If you have the default party, it can be much harder or easier than you are thinking just from the skill points you assign. On the default party, I recommend you max out the Freemage light skill as much as you can (master in Act 1) as a priority. I doubt you will have master level at the lighthouse boss, but just have as many points as possible. Every time the Freemage levels, do 2 points magic, 1 point spirit, 1 point vitality. The celestial armour spell will be very good at this point, saving you from a lot of damage.. it will let you breeze through pretty much any of the trash mobs in the entire act, likely without ever needing a heal potion. Once you have master light, take advantage of dark magic, if you can get it to expert the Sleep spell is very good crown control for act 1+2.
Admittedly, I did find the default party somewhat lackluster, especially on warrior difficulty. The Dwarven Defender may be great endgame at GM level, but start/mid game he can't hit worth spit (so lots of missed taunts) and his damage output is very poor. The Orc Barbarian does good damage with a 2H, but does take a lot of damage in return. The Elf Ranger is very weak IMO... ranged combat (even after the buff in the patch) is not that effective, and the melee isn't anywhere near as good as other classes. I ended up making her a caster which can get you through mid game, but since she caps out at master level makes it quite hard at the end. The Freemage is a good one, and is the only class who can use Dark magic. Sleep and Purge are incredibly useful, as is Dispell if there are no other classes up to cure debuffs.... and of course Whispering Shadows to find secrets.
Honestly, I had a waaaay better time after I rerolled. I went with Human Paladin, Elf Druid, Dwarf Runpriest and Elf Bladedancer. The GM Light Paladin can do some decent tanking, is a pro with Celestial Armour, and can heal in a pinch (not to mention break curse and rez). The Elf Druid (Earth Magic) is the primary healer, GM regeneration is very strong, especially combined with stoneskin and the poison AOE is quite good as well. The Dwarf Runepriest does good damage with fire magic, but the real DPS comes from the dual wield dagger Elf Blademaster. No magic, no ranged, pure melee DPS, very nice output and becomes ridiculous near the end of the game.
At first I didn't want to reroll as I felt it took me too long to get to where I was, but TBH I made it back up to the same stage as my first part in only a few hours (I was about 50% through Act 2 the first time and it took AGES because the combat was so hard). With this new group, enemies just melt in front of me... the only bad ones so far are ones who can do mana burn. But if I can get Celestial Armour up + Stoneskin, victory is pretty much in the bag
