"avatar for RaceBandit RaceBandit Levelbug31 Aug. 12, 2009 I hereby issue the following challenge: Beat a score of 18481 on Sandbox mode 1-102498625-16." I did 18715 :]
The saves are inside "Documents and Settings//Application Data/Macromedia/Flash Player/#SharedObjects/" directory. Search for yolo.swf directory and delete "save.sol" inside it.
Helped me.
Simple. Just DO NOT buy mana pool upgrades, always start level with 20 mana. Upgrading it during the level gives you mana regen, but buying the upgrade does not (and there is a limit of 9999 mana).
So just buy mana regen, faster unit create time and dragon upgrades. Start level with two or three mana pool upgrades, buy some junk to start with, upgrade pool to 640 or 1280 and start spamming dragons.