Fort Triumph

Whilst not a full guide, here are some tips that should get you through the campaign with relative ease.

1) The campaign is much harder at the start than at the end, especially the first couple of missions. Clear them and you'll be fine the rest of the way.

2) You can constantly reset battles to get a set up that goes in your favor, however you cannot save progress mid-mission. If you save during a mission, reloading it will just act like a reset.

3) You can take your time on the overworld, to an extent. During the first two Acts, you can quite happily explore the map, with out too much worry over the A.I coming in to take over your base or wipe out your team, but during Act 3 that changes. In Act 3 there are 2 enemy A.I to deal with, so you have to be a bit more focused on the overworld. My strategy was to use the main team I'd used through the whole campaign to go round the map and wipe out the A.I units walking around. For the most part you'll be stronger than them, so it shouldn't be too hard. In the mean time, build up a second squad at your base, then once there's 4/5 team members, send them to camp in front of one of the enemy bases. Doing this limits the A.I's units to level 6 when they spawn (same as your new squad) but importantly they can no longer roam the map. Build up a third squad and do this to the 2nd A.I, and you'll then have free reign of the map with your main squad to beef them up for the final campaign missions. Getting to level 20 will really help.

4) Keep multiple back up saves in case of failure. I always had one save held at the start of an Act in case I really messed up, then I'd have 4-5 rotating saves that I'd use before each battle in case it went really wrong. The only way you can fail the campaign is if you loose all your units and your bases, other wise you can keep going.

5) When your characters level up, if you're not happy with the skills on offer, wait until they level up again and you'll get different ones to choose from. As for any 2nd/3rd teams you build, you can only carry over 4 characters between acts, so mainly focus on the main 4 squad members, the rest are mostly just fodder for the first 2 Acts, but they can be handy in Act 3.

6) My set up for the final campaign was as follows (a * indicates a highly useful skill, all skills were maxed and characters level 20);

Paladin - Hammer Strike*, Kick, Healing Aura*, Rally, Evasive Instincts*, Holy Shackles, Bolster;
Barbarian - Claws Attack*, Kick, Daredevil Stance, Dash and Slash*, Evasive Instincts*, Bloodlust*, Terrify (get Frighten instead);
Mage - Magic Arrow, Whirlwind*, Fireball*, Chain Lightning, Vortex*, Dash and Slash*, Healing Aura*;
Ranger - Arrow Attack*, Grapple Hook, Quickshot*, Pacify, Knockback Arrow, Dash and Slash*, Encourage;
Ranger - Arrow Attack*, Grapple Hook, Quickshot*, Pacify, Smoke Bomb, Healing Aura*

I definitely recommend two archers or two mages, either for the double Arrow Attack (100% hit change at max) or the double Fireball (huge AOE at max). I also never paid any attention to equipping items, so don't worry too much about that.

7) Take your time during missions, once you kill everything in an area, skip a few turns to let your skills reset, in campaign missions, the enemy won't engage with you until they become visible.