tip for hard mode: upgrade mana regen. get the mage, give it the kongregate face (sold @ shop) and keep buying the better staffs for it. Every game keep spawning those mages and keep on spamming the poison skill. You will get through all levels easily until the boss.
For the boss you need the Tornado skill (last skill you can buy), start again with spamming those mages until you get to the boss. The boss will kill them, you just need to spam the tornado and spawn a few tankers every 5 seconds to keep him busy from walking.
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