The Badlands is the sixth multi-player "dungeon," for level 45-50 characters.
The basic strategy for this boss (and the one in the Garden of Death) is to stay alive longer than the bad guys. Expending rage on flashy attacks (or flashy heals) will kill you.
Before you attack the final boss, check:
The mages' job is to keep the rest of the party alive. The archer's job is to freeze the enemies so that the mage can keep up.
The mage should open with Suntoria. Resist the temptation to use massive attacks; you'll need your rage for healing.
The boss worm shows up with two little guys. The little guys hit as hard as the boss, but they're weak on hp, so knights and archers should use aoe attacks to kill them as quickly as they can.
The archer should shoot Freeze every time it's available. Don't hesitate to use it. Freeze as soon as you can so it can countdown to the next use. Every time you Freeze, you buy time for the mage to rebuild rage and the healing spells to cycle through their countdown. The most common cause of failure in the Garden of Death is when the archer gets carried away and uses big attacks instead of freeze; resist the tempation to show off how strong you are and keep on freezing, and you'll win.
The boss's bleed attack does 4000 hp damage per round, so the mage must have Purification to counter it.
Blessed Light uses up 60 rage. If you have two mages, it might be useful, but otherwise it can be fatal. You can get a full heal in one round, only to exhaust your rage so it's not there when you really need it.
Knights should use their bubbles to reduce the amount of damage they take.
Everyone should be prepared to use healing runes, and use the first one early so that it will have time to countdown. The second most common cause of failure in the Garden of Death is when the knights or archer put off using their healing runes, so that the mage falls behind trying to keep them alive.
In addition to keeping Suntoria going and using Purification to counter bleeding, the mage should cast Restore (individual heal) every time it's available. Don't hesitate to cast Restore; cast it early and often so that it can cycle through its countdown and be available again.
Don't get discouraged. If everyone does his job correctly, you'll win!
Never, never, never, never try to give instructions to the mage during the boss battle. Do NOT call for healing or purify, ever. The mage will be concentrating on keeping the party alive, and only the mage will know the status of his rage and countdowns. All you can do by trying to boss the mage around is cause the party to lose the battle by distracting the mage or, worse yet, demanding that the mage type explanations while while he's busy keeping you alive.
Just keep on fighting, use your healing runes, and show respect for the mage's ability.
One exception might be if you're doing a training run for a mage on his first encounter with the Garden. But even then, if you have to call out instructions in real time during the battle, you didn't do a very good job in the pre-mission briefing.
If you're obsessive about demanding that the mage cast heals to save your hp packs, please let me know in advance so that I'll know not to go to a Garden Party (or anywhere else) with you.
Encourage the 55+ mages in your guild to get their exp runs done early in the Garden of Death and Tarraton's Lair so they can help you through the Badlands without using up their real multi-player dungeon runs. :)