Use 37 int for 20 regen, it's op at level 20.
Use the same build that you are now but no bov 6 heal. The point of 20 dex mage is to kite out str mage's bov. Also 40 more hp every 3 seconds is more often than not better than 12 armor for 12 seconds.
Fbow is a lot better for nuking since that's what you'll mostly be doing. But since str mages can get up to 100 armor you should use paw/candle for better armor and regen until their bov is all gone. Then switch to fbow and nuke as hard as you can. For rhinos just keep kiting them and hope they run out of mana before you. For bears just kite them, 12m fire is really good against bears until they get high beckon. For foxes and birds just try to heal off their debuffs and before combos and such, try to stay out of auto range and run away to heal if you get low.