Battlefield seems small, and why the hell would you start a battle in melee?! 'O'
Having a large party contributes nothing if all they can do is basic strike~ Why not make a more compact team with a broader array of spells.
Try playin with Pushes/pulls/charges/teleports/ swaps[Does engine allow it?] (General mobility) use the tactical combat you've impletend to its greatest extent.
Since its open world the encounter mobs need to have special mechanics, which will make'em dangerous even vs a lvled party:
Like lvl1 Spiders can poison which should last a long time and prove a danger w/o countermeasures
Or some random magical gremlin castin debuffs and teleportin around xd
Maybe a zombify effect to make healing deal dmg instead '.'
Invisible place swapping faires xD
Next one is terrain manipulation, a tactical combat can be made so much greater with turning earth to mud, setting up a fire wall, or creating a glyph that is a wind speeding up anyone crossing the glyph cell. (Or make it directional with it speeding you up when you for for example north and slowin y when going south)
(Then there is a topic of elemental resi/weakness, but you got that in EK so will probs be fine)
LVL's in open world game should not give a lot stats ( but you got that pretty much nailed in Exiled Kingdoms)
Lore will be good cuz EK had a good lore
Sure Hope the game would be less grindy than EK tho '.'