A variation to Bombot teams for beginners could be:
Deep Borer
Bombot
Bombot
Ship Canon → Edit: Steam Turrent from Adana would make a better pairing because:
No traits needed, but it would be better to fully trait Deep Borer at least. The Banner can be any combination of Blue or Brown because with blue mana you will fill Deep Borer fast, faster if you unlocked Water Link on it’s traits, and extra brown for the rest of the troops. Bombots should be able to wipe the enemies, but if anything is left the explosions may give some mana for Ship Canon to finish the job. Even a summoned troop alone should die from Ship Canon’s damage because all three shots will hit it since it’s the only “random” troop left.