There are two different ways to win:
1. HP Method
Reduce your opponent's HP to 0 using whatever strategy you choose (Hero's melee attack, spells, Hirelings' attacks, Hero's ability.). Upon knocking your opponent out you win the battle.
2. Portal Method
If your Hero (or your opponent's Hero) reaches the opposing Portal tile and can survive for one full turn, they will win the match.
- Note: using a Hireling to occupy the opposing Portal tile will not win the battle. It must be a Hero.