Im not too far in, but kinda getting wrecked by some of the tougher monsters. Ended up restarting after hitting the 3rd floor of the light house where you have to fight two elites, and 2 normal enemies as the first battle. Finally got past that with out too much trouble, but boss is wrecking me hard. I really cant find anything else to kill. Chars are level 6 I think.
Your skills must be all over the place. You NEED two things to progress well. Celestial Armor and Rejuvenation. CA comes from Light and Rej comes from Nature. One blocks X amount of DMG and the other Heals the whole party + Rej.
Yep, there's no enemy respawn in this game, thus, dry each area out of experience before heading to the next one. If the lighthouse is too hard for you, clear the entire Tirya bay, move on to the forest and even clear some parts of the Ashen hills before heading to the lighthouse.
Remember that resting is your friend; instead of chugging potions one after another; you can get up to six supplies in Sortigal, or up to nine in the itinerant merchant (the wagon) in Ashen Hills. Seems game doesn't mind that you take years (in game time) to complete so use it in your advantage.
Also... build somewhat tanky on all your party since devs were too lazy to add front and back rows to this game. While several places recommend you to go full DPS (specially casters), you NEED life points so enemies don't start one-shotting your casters five times each battle when they start getting several attacks per turn, so place a point on endurance from time to time.
Finally, positioning is extremely important in M&MX, since kiting is no longer possible (a looong step backards since M&M 7-9); in Lighthouse Lv3, place yourself in the hidden room (the tile to your left right where you enter the area) so enemies can only come from one side. Being attacked from several sides is common in this game if you don't position yourself correctly, and specially at low levels, very dificult to survive. remember that, as long as you're not involved on melee combat, you can move your party if ALL of them have not performed an action yet.
"Good roleplaying does not preclude fireballing their asses" Vaarsuvius, Order of the Stick