gas trap for djinn rush near the end. Gas radius as small as possible is ideal. Mine is around 1.5k
web wall at top stairs to slow down ogres/debuff. If your stats aren't high enough (like mine), they'll reach the towers and swing at them and hit the crystal too
Towers might get hit, but healing from forest golem and tboost should be more than enough
Hint 3: tboost here can get webbed, so reflect walls for safety. Can't find 100% safe spot for builder, but even without active builder there shouldn't be a problem