I'm an elite pro pure dexbird and a bird should focus, follow the bear in, shattering scream when he sees the bear beckon, thorn wall once the mobs are gathered (it sets up the nature strike combo when the mage lightnings), blast shot (for his own self combo) and evade. If the bear hellscreams after the nature strike then you will activate a mega combo.

Also, bears shouldn't waste time trying to kill every single mob. Rush in, beckon to a wall, step back and stomp mobs back into the wall, then hellscream. If the mobs health bar is less than 50% the bear needs to leave and go gather the next group. If not then continue to taunt and beckon the mobs away from the mages and birds.

Most mages either don't heal or heal whenever it's available. A pro mage will save heal until he sees the tanks health getting low then cast it. There's no sense in casting heal when you're running to the next set of mobs and everyone has used health pots and has full health. Watch your tanks health and save you heal until he needs it!