Keeping your spells up when you are an avatar becomes a pretty tedious exercise. I suggest making an avatar skill that would make those spells last forever, but at the cost of your mana regen.
The skill would convert all your spell times on spells that last longer than 10 minutes (to exclude things like aegis and wraithform etc) into mana cost per minutes (i.e stamina lasts 20 minutes and costs 20 mana to cast, which will equal to 1 MR per tick, so you mana regen would go from 100 to 99), but the spell will be constantly up without any need to recast it every 20 minutes.
The skill does not provide any character power, but it reduces the annoyance of constant recasts, pretty much the same ideology as gorge skill.
Suggested level: 20 avatar
Usage: <skillname> "spellname"