a really really easy way to win late game is to have all the "storm" spells equipped, along with wealth and planned assault. Then once you have enough at the beginning for your first spell you use it, and just keep using storms of whatever there's most of on the board. THEY DO DAMAGE and they keep your mana full, and they recycle the board so quickly that you can keep getting those rage gems with planned assault.
I was doing 112 with each rage attack(nymphs spellbook) and 30-50 with each storm.
advice for early game: quickly get the defensive tortoise then start with him and build all archers. Save enough mana for healing each time he gets low and you'll never lose him