Warbound (Bog Standard Isekai #5)

No battle plan survives first contact with witches.Armies have risen, the great machines of war are prepared, and the battle beasts are straining at their
leashes. Despite Arcaena’s every attempt to prevent it, the full might of three kingdoms have gathered
at her borders. From all outward appearances, Brin is finally on the stronger side.

But no [Witch] should ever be underestimated, and an ancient [Witch Queen] with her back against the
wall is more dangerous still. While fighting in the army, Brin will feel the pain of curses and poisons even
more than the strength of ravenous undead, fearsome monsters, and trained human soldiers. Arcaena
has had centuries to steep her nation in her power, and every inch of land will resist them. Worse still,
the world’s strongest warrior, Lothar the [Paladin], will do everything he can to undermine the war from
the inside while the soldiers are fighting enemies on the front. ... more>>