You can find Grim Batol dungeon within Twilight Highlands.
The coordinates are (19.9,54.0)
1. General Umbriss
/i Attacks current target with Bleeding Wound, heal them above 90% to remove this. Blitz charges on a random players location, move away. Faces a location & fires a ground tremor, avoid this cone. Summons Troggs to fight.
Heroic Differences: When a Maligant Trogg dies it will cast on boss & Dwellers Modgud’s Malice, this increases bosses damage by 100% for 20 sec & transforms Dwellers into Maligant Troggs.
2. Forgemaster Throngus
Heroic Differences: Flaming Shield (Shield Ability): fire erupts from shield in a frontal cone, avoid this. Burning Flames (Swords Ability): Inflicts a fire dot to his target, can be dispelled. Lava Patch (Mace Ability): avoid fire patches that appear on ground.
3. Drahga Shadowburner
/i Blasts players with Shadowbolt. Flaming Spirit chase a random player, kill before they reach player. At 30% Valiona joins fight. Avoid frontal cone Valiona’s Flame. Move out of pool of Seeping Twilight.
Heroic Differences: Valiona: Avoid the large cone Devouring Flames, further away you are the less damage you take.
4. Erudax, the Duke of Below
/i Fires Binding Shadows at a players location, it drains life then healing boss for high amount, avoid this. Tank takes high damage from Feeble Body effect. Careful of damage from being inside storm. Interrupt Faceless Corruptors Umbral Mending.
Heroic Differences: Shield of Nightmares is cast on Faceless Corruptors, do not attack them during this to avoid shadow dot on all players.