From Felwood Bounties Level 26, it seems that my mercenaries just don’t have enough health.
Is it best to just to go back and play The Barrens over and over?
That’s probably not the best way to go, since max level is 30 anyways and you will hit that soon. To get stronger you should think more about team composition and tactics. Also the Barrens don’t have good coin rewards.
What team are you using? Maybe you have weak mercenaries, that don’t synergize well.
If you run Millhouse, Tyrande, Xyrella, Cornelius, Samuro and Grom/Roame it’s not too hard as long as you pick the correct starting team.
Millhouse and Tryande have the Arcane Synergy, Xyrella and Samuro the debuff → attack synergy, Cornelius in teh middle with teh taunt ability keeps you’re other guys alive.
Just try and avoid sending out a starting team into more than 1 opponent that critically damages them.