There is also a necromancer.

The Necromancer is pet and area of effect spell caster. Warlock has 3 schools of magic, 2 of them share the charge bar, its a unique two stat bar. You charge up one or the other for stronger effects in that school. The ranger runs off of 'charges'. Cast a buff, gain charges for a specific skill and then auto attack to have the charges proc. The paladin buffs with your standard buff style. Cast the blessing on yourself and attack. ranger and paladin are kind of counter of each other. They are all rather fun to play imo.

Synergies itself was designed to not need other mods, a lot of people still install essentials. Its up to you. Synergies is balanced on itself only.