The real Lich(First one you see) shoots 5 black orbs out at you in a fan that do about 60-70 damage.
The copies shoot tracking bolts, summons eyeball enemies.
Summons up to 4 copies of himself (total of 5 of him running around).
The real Lich teleports from place to place continuously. That is the enemy you need to defeat.
Use the 4 pillars in the room to your advantage to more easily dodge his projectile weapons.
You need to continue to run and hit him even if it is just one attack. This is an attrition fight.
If you simply rush at the Lich, you can easily defeat him in under 30 seconds as the Paladin. If lives are not a concern, you can just attack him head on and lose 1-2 lives. This is assuming you put decent investments into attack and defense.