You can find the Mana-Tombs dungeon within Terokkar Forest, Outland.
The coordinates are (39.5,61.9)
/i Void Blast fires bolts dealing shadow damage to 5 players & knocks back. Dark Shell reflects spells & does shadow damage to melee attackers.
/i Crystal Prison stuns a player & inflicts nature damage. Inflicts nature damage to players & stuns them with Earthquake. Damages all in front with Arcing Smash, avoid this.
3. Yor (Heroic Boss)
/i Stomp damages & knocks back all nearby players. Damages all in front with Double Breath, avoid this.
4. Nexus-Prince Shaffar
/i Casts fire & frost damage spells. Blink teleports boss forwards. Ethereal Beacons inflict arcane damage, they destroy themselves when summon Ethereal Apprentices. Ethereal Apprentices cast Fireball & Frostbolt, interrupt these.