All of the enemies are weak to slash type attacks, and most are water element. All enemies are also weak to paralyze and stun. After Scorpion Sentinel's HP has reached a certain point, 2 more soldiers will show up as reinforcements.
While there are a lot of enemies in the beginning, most of them will stay in place and use buffs on their first turn, and the 2 spellblades will use magic shield buff on their team.
The gunner soldiers often uses a 2 hit attack, and can also use a ranged explosive damage in an area. Since there's a lot of them, make sure to stack up on missile resist for your tank so they don't get chained to death.