The 10 hydras.... Not impossible. Just really hard. Get up to the point where you can farm the three hamsters level and do that until you can farm the 3 hydras level then the 5 hydras level. Then farm that until you have at least 150% in both damage and health and at least 70-80% in revive. Then get lucky and hope they don't do that attack that deals mega damage and sends up up in the sky.
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