I think the tactical battles should include a counter-strike option.

I just won a battle with 1 sovereign vs. 6 spiders without ever being hit once, and never being crowded.

My sovereign has 2 moves. there are 5 big spiders and 1 small with 1 move each.

I use terrain to make sure one spider closes in, alone. I hit it twice and it dies.

Next turn, another spider closes in. I hit it twice, it dies.

Repeat until there are 2 spiders left. One of them circled the pond I had used to prevent them from swarming me. Since I'm twice as fast as them, it's easy to move, hit and kill the small spider, wait for the big to approach and hit it twice to kill it.

End result: Although I should have been swarmed, I haven't ever been hit. It's not so much good tactics as abusing the system.

If units attacked just after closing in (expending all remaining movement points), I couldn't have avoided being hit.

If units counter-attacked after I hit them, or simultaneously, I would have suffered some attrition.

There may be other solutions, but right now it really feels too formulaic and easy to abuse.