Force cube does not need to hit your primary target, for example you can end your run by throwing a +15 force cube right next to you.

Post screenshot of your game history so we can see what's killing you.

Use scrolls of identify on scrolls. You can also cook them in an alchemy pot to turn them into stones, identifying them in the process.

Also you're guaranteed to get 3 scrolls of upgrade in each chapter.

Example mage strategy build.

EZL-FAN-WQX 6: Wand of Lightning +1 (crystal chest) 7: Sword +3 (cursed) 8: Wand of Lightning +3 9: Wand of Lightning