Help with LVL 20 Mage

[Motivating]

So would this build be viable: 6 Heal, 6 Light, 4 BOM, 1 Fire, 1 Frost, 1 Drain?
And what would my order be? I havent used drain before so I dont know timings/range/delay etc.

I use this but with 5BOM no drain, very very tanky. Mage fights and rhino fights are mostly regen fights but are still winnable