It is Ursa the desert fire lord, he has 2 phases!
First phase is quite simple just tank and spank!He will be casting only rejuvenation spell and deal hard chaos damage.
After some time second phase comes, ursa will summon 3 channeling wards to keep him invurneable while he is casting HUGE rain of fire, you will have to do quick to kill channeling wards or you have failed, wards are invurneable to magic attacks and spells so it will be pretty hard to kill them since 3/7 units have magic attack.
You will have to run and hide with your spell casters while melee units are killing the wards, only healers have to be nearby to heal your melee untis, for this phase i suggest druids bear form (he has normal type damage in bearform).
After wards are dead ursa will be vurneable again and he will stop casting rain of fire.
Then you just finish him.

Updated, added opponent player so you can play this game on battlenet, added 2 new bosses and more epic drop and old ones are little bit reworked, more items are added to trader in camp.
Added new unit with his own class item, the huntress!

Boss and mobs
Bosses' health and damage has been increased by 20-50% depends on boss level.
Trash mobs have been reworked also, they have 5400 hp up from 3000.

Units
Battlemaster's slam will now deal 200 + 3 damage per mana point on cast, and will taunt enemy unit.
Battlemaster's Ground slam now deals 200 damage up from 100, and has chance to taunt enemy units in 350 range.
Earthgiver's Earth shock base damage is reduced from 150 to 50 and damage based on mana points is downed from 5 to 3 per point.
Earthgiver's Pulverize now deals 250 damage per unit, up from 150, and has chance to taunt enemy units in 350 range.
Druid now can cast cleansing totem while shape shifted, and totem's mana cost is downed to 75.
Druid's Nature's blessing healing is increased from 500 to 1000 over 10 seconds, but now it will receive 50% spell power less from items.
Dark Cultist's Unholy seal has new icon, but effect is still same.j
Dark Cultist's Siphon life will now properly damage all units in 250 range from target unit.

Items and drop
You cannot carry more then 1 item per type, that is fixed now.
Trash mobs drop is changed, added more items and Amulet of spell shield is replaced with Tears of Nature which increases spell power by 50 and reduces magic damage received by 20%

Intro story
Since earthsong expedition found human and troll rebells extreemlly hard enemies, they head south to crossroads to find some help but in the way there they found mysterious Storm hag canyon.

Bosses and Trash
Blood mage's spawning trigger has been removed and he is spawned on start of game, he has inferno phoenix and flame strike abilities.
Added 2 new bosses :
1) Harpy storm queen
2) Ogre overlord
New trash mobs :
1) Harpy warriors

Units
Shaman's and druid's Ancestral spirit now has reduced mana cost downed to 150 from 200 as well as cooldown from 30 to 15 seconds.
Druid's Feral bash now has 15% chance to deal 150 damage, up from 10%.
Spiritualist's healing wave now has reduced mana cost from 75 to 50 but increased cooldown from 2 to 3 seconds.
Huntress' flaming arrow will deal additional 500 damage over 10 seconds.
Huntress' Crushing shot will deal 1000 damage per targed, still up to 2000 max damage.
Huntress' Precision has lowered chance to deal critical strike from 15 to 10% but damage multiplier is increased to 5.
Battlemaster's Warcry now costs 30 mana downed from 50 and increases damage done by 65.

Items
New item added, relic of the blood thirst, this is Battlemaster's and Earthgiver's class item, it will increase total health by 300, attack damage by 20 and provides 20% life steal ability to your attacks.

Intro story
I have added new unit, the Monk, to help party in killing bosses.

Bosses and Trash
Added Breath of fire to centaur, harpy mobs and harpy queen, breath of fire beside direct and damage over time will decrease healing received on affected targets by base heal amount, just spiritualist's healing wave will be reduced by 300.

Units
Shaman's healing wave now has 700 base power.

Lets tell something about Monk :
1) Nether Waves -> Heals all friendly units in 500 range from target point over next 5 seconds for 50 + 1/2 spell power per second.
2) Nether Strike -> Stuns targeted enemy and summons 3 images of monk to strike targeted unit, images will deal 900 damage in total.
3) Disciple of Mind -> Monk's attacks will steal mana from enemy and spread it to nearby friendly untis, 50 mana is stolen per hit.
4) Ancestral Spirit -> Same as druid or spiritualist monk can resurrect friendly dead units.


Items
Nether shard of mind, increases monk's health by 300, attack damage by 30, spell power by 50, and doubles mana stolen mana shared.(Monk will be still stealing 50 mana from enemy, just when stealed mana will be doubled and then spread to party members)

Game Play
Added ranking and token systems.
By killing bosses you will be getting achievment tokens, these tokens you may use to increase your rank in Earthsong Clan, by increasing rank you will be rewarded with health/mana or attack bonuses depends on your class.
(There is description ingame that tells everything about that)

Bosses and Trash
Ursa has been reworked, rejuvenation has been removed from his set of abilities, but new one is added it if marked for first phase since ursa is under 20k hp first phase is goin to start, he will be constantly setting up 10 fire bombs around him after 6 seconds bombs will explode dealing 300 damage to every unit in 150 range.
Second phase is moved to 7000 hp, and waves of fire will deal 100 damage + 25 per second, and channeling wards now have 1500 health.
Now all bosses will give Earthsong Token beside 500 gold reward, tokens you may use to buy newly added epic items from trader, to help you get items if bosses doesnt drop.
Forest lord dryard guardians have life regeneration aura no more and his resurrection ability has been removed cuz of mass resurecting fungies.

Units
Druid's Cleansing totem now has 100 mana!
Earthgiver's health is increased by additional 100 points.
Monk's abilities will receive less spell power from items.
Monk's Nether wave has new icon.
DarkCultist now is Mind Priest.
Monk's images will deal 50% more damage.

Items
Several items are added to trash drop, and one new epic is added but that one cannot be drop from bosses Trader in camp can offer him for 3 Tokens, it will increase your spell power by 300 and total health by 250.

I will announce next version in few days, for now i am planing to make briliance aura gives 3 mana per second down from 5, and pass it to spiritualist, while Mind priest will have new ability "Mind Shield".

Current version might be bugged, i have not fully tested it, so i need you to make some coments.If you want to try it in single player mode, you have to set up all other players to be computer players and you will receive additional Earthsong tokens and 900 gold, so you can buy items for trader and with little luck you will be able to solo 1 or 2 bosses.