Tasks

Those tasks can be received from NPC Grizzly Adams, which can be found in every city.
Example how to take task: Hi > Tasks > Medium > Vampires > Yes
Example how to cancel task: Hi > Cancel > Yes
Most of these tasks cannot be performed together with client tasks, although there are exceptions, details can be found in the "Blocks client tasks" table.

The reward can be checked in the table below:

Easy

Task Name	Monsters	Kills	Level	Reward	Blocks client tasks
Weak Minotaurs	Minotaur	500	20	Dragon Shield, 30 Minotaur Leathers	Yes
Weak Orcs	Orc Spearman, Orc, Orc Warrior	500	20	Warrior Helmet, Ring of Healing	Yes
Weak Dwarfs	Dwarf, Dwarf Soldier	500	20	Spirit Cloak, 30 Iron Ores	Yes

Task Name	Monsters	Kills	Level	Reward	Blocks client tasks
Strong Minotaurs	Minotaur Archer, Minotaur Guard, Minotaur Mage	500	40	Nose Ring	Yes
Barbarians	Barbarian Bloodwalker, Barbarian Brutetamer, Barbarian Headsplitter, Barbarian Skullhunter	600	40	Spellbook of Mind Control, 20x Sudden Death Rune, Energy Ring	Yes
Demon Skeletons	Demon Skeleton	400	40	Demon Shield, 10 Demon Dust, Stealth Ring	Yes
Vampires	Vampire	300	40	Vampire Shield, 10 Vampire Dust, Stone Skin Amulet	Yes
Necromancers	Necromancer	300	40	Boots of Haste, 40 Blue Piece of Cloth, 100 Power Bolt	Yes

Task Name	Monsters	Kills	Level	Reward	Blocks client tasks
Quaras	Quara Constrictor, Quara Hydromancer, Quara Mantassin, Quara Pincher, Quara Predator	400	60	Skull Helmet, 50 Small Sapphire, 30 Fish Fin	Yes
Hydras	Hydra	800	60	Swamplair Scales, Ring of Healing, 40x Ultimate Healing Rune	Yes
Frost Dragons	Frost Dragon	800	60	Angel Bow, 300 Sniper Arrows	Yes
Dragon Lords	Dragon Lord	3000	80	Firewalker Boots, 5 Small Enchanted Ruby	Yes

Task Name	Monsters	Kills	Level	Reward	Blocks client tasks
Demons	Demon	500	100	Helmet of Demonic Fire, Angelic Ring, 80 Small Diamonds	Yes
Grim Reapers	Grim Reaper	1000	100	Boots of Great Haste, Time Ring, 90 Small Amethysts	Yes
Juggernauts	Juggernaut	800	100	Golden Boots, Golden Legs, 20 Gold Ingots	Yes
Powerful Undeads	Betrayed Wraith, Lost Soul, Blightwalker, Dark Torturer, Undead Dragon, Hand of Cursed Fate	1000	100	Magic Ice Armor, 90x Avalanche Rune, Amulet of Loss (3 charges)	Yes
Castle Guardians	Crusader, Royal Halberdier, Champion	2000	100	Demon Legs, 200 Infernal Bolt	Yes
Dreamhaunters	Frazzlemaw, Silencer, Shock Head, Guzzlemaw	3000	200	Nature's Fury Helmet	Yes
Frozemoths	Frozemoth	2000	200	Celestial Archery Helmet	Yes
Fear Creatures	Retching Horror, Choking Fear	2000	200	Amethyst-Encrusted Helmet	Yes
Sight of Surrenders	Sight of Surrender	1000	200	Obsidian Gaze Helmet	Yes
Dreadscale Hydras	Dreadscale Hydra	3000	300	Crystal Quiver	Yes
Dark Furys	Dark Fury	1000	300	Onyx Sentinel Shield	Yes
Strong Lizards	Lizard Rider, Lizard Spellweaver, Lizard Warmaster	3000	300	Crystal Blueguard	Yes
Daily Bosses	Swampling, Archangel Marcus, Deglorath, Archdemon Arnan, The Dark Elfith, Frostbreath, The Hand Rider, Frozanverian, Gaz'haragoth, Sungorath.	200	400	Sorcerer - Eclipse Legs, Druid - Sunward Legs, Paladin - Blaze Armor, Knight - Frostwind Armor	No

This is diffrent type of tasks you can show the panel by clicking the red marked button from top-left of the client:

In this type you can get only experience or gold.
You can choose how many monsters you want to kill yourself.
You can start a task and pause it whenever you want, but only in a protection zone.