You can find the End Time dungeon within Caverns of Time, Tanaris.
The coordinates are (64.3,49.5)
At beginning take the Time Transit Device to travel straight to a Dragonshrine.
You will gain aggro of nearby Time-Twisted mobs, pull them into the pool of moonlight (easier to kill). Continue this until boss appears.
Collect 16 fragments from the area, this will summon boss.
You will need to jump over the platforms to reach boss.
1. Echo of Tyrande
/i Avoid standing near boss during Dark Moonlight (purple pool). Interrupt Stardust. Dispel or avoid Moonlance (travels & splits along ground). Summons Eyes of the Goddess that circle round boss, avoid or dispel Piercing Gaze of Elune (arcane balls).
2. Echo of Sylvanas
/i All spread out (boss does lots of aoe). A wall of walking Ghouls will move towards you, focus kill 1 (put skull on) to clear a path through. Do not stand in the purple shadow clouds. Dispel Shriek. Move out of purple circle from Blighted Arrows.
3. Echo of Jaina
/i Boss Blinks around. 1 dps run over Flarecore embers on ground, you have 10 secs before they detonate. Avoid Frost Blades, boss sends ice flying forward. Frostbolt Volley reduces movement speed. Pyroblast inflicts lots of fire damage to current target.
4. Echo of Baine
/i Smashes ground & destroys nearby platforms, move to another when Pulverizes yours. Stacks Molten Axe on himself, deals more damage when touches lava. Dispel Molten Blast on tank. Throw Totem back at boss.
/i Don’t stand near boss for Temporal Blast. Avoid standing in Distortion Bombs that land. Noz grants players Blessing of the Bronze Dragonflight. Hourglass of Time can be used 5 times during fight, restores party to full health/mana & removes bombs.