Also, if you can, be sure to buy healing items and mana potions since IIRC, there will be no more new equipment coming to the shops from now on so you can pretty much waste all your gold on consumables.
If you are still having a hard time, be sure to finish the hive quickly using spells and don't try grinding for XP on the bonus units.
If you are still having a hard time, be sure to finish the hive quickly using spells and don't try grinding for XP on the bonus units.
Can you tell me what weapons you use? What are the most powerful skills you have? IIRC, I always have a healer and mage (Pike can fulfill both of those roles easily). And the mage's AoE spells are powerful, I believe you already have access to the Darkmoon spell? Be sure to give your mage plenty of mana (through wearing robes or using pots). Also, new armors are not as essential as weapons as the stats you gain with each upgrade are pretty small.
As they are triggered, using spells ignore the armor & evasion of your enemies. So if you're having a hard time damaging the enemies, these are your best bet.
Lastly, don't ignore attack and armor types. Always hit the weak spots & don't expose your units if they're weak to certain attacks.