Timeless Champion

As listed in the criteria, there are 31 total new rare spawns on the Timeless Isle, 13 Rare and 18 Rare Elite creatures. The location of the mobs is as follows (in alphabetical order):

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• [npc=73174] - varied, can spawn next to each Cauldrons of Flame in the corners of Ordon Sanctuary
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• [npc=72775] - varied, can spawn at various spots in the Croaking Hollow
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• [npc=73171] - varied, patrols between the two bridge at the Blazing Way area
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• [npc=72045] - 25.3 - 35.8, north of Horde camp
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• [npc=73175] - 54.0 - 52.4, right before the broken part of the bridge
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• [npc=73854] - 44.5 - 69.0, SE of central arena, can be summoned by pulling a [npc=72095] from the south to its location.
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• [npc=73281] - can be summoned by [npc=73279]'s guaranteed drop: [item=104115]
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• [npc=73158] - varied, wandering in the forest around the central arena.
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• [npc=73279] - varied, swims around the whole island
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• [npc=73172] - varied, can spawn at various spots outside the Ordon Sanctuary
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• [npc=73282] - 64.8 - 28.8, spawns in the Ruby Lake on top of the high cliff east of Ordon Sactuary.
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• [npc=72970] - 62.5 - 63.5, Red Stone Run
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• [npc=73161] - varied, wandering around the west shores
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• [npc=72909] - varied, can spawn at various spots around Old Pi'jiu village
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• [npc=73167] - varied, flying around the Blazing Way and Firewalker's Path areas.
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• [npc=73163] - varied, can spawn at various spots in the forest around the central arena
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• [npc=73160] - varied, wandering in the forest around the central arena.
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• [npc=73169] - 52.0 - 83.4, Firewalker Ruins
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• [npc=72193] - 33.9 - 85.1, at the jetty south of Old Pi'jiu. Can be summoned by speaking with [npc=72151] at the docks
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• [npc=73277] - 67.3 - 44.1, Blazing Way area
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• [npc=73166] - varied, can spawn at various locations around the shores
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• [npc=72048] - 60.6 - 87.2, available when you see [npc=72032] standing on the deck of the sunken ship.
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• [npc=73157] - 45.4 - 29.4, spawns at the bottom of the Cavern of Lost Spirits
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• [npc=71864] - 59.0 - 48.8, Mysterious Den, can be summoned by breaking the cave-in.
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• [npc=72769] - 45.4 - 38.9, Cavern of Lost Spirits
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• [npc=73704] - 71.5 -80.7, on the upper deck of the pirate ship at the bay next to Croaking Hollow
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• [npc=72808] - 54.6 - 44.3, inside a cave
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• [npc=73173] - 45.4 - 26.6, in the western court of Ordon Sanctuary
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• [npc=73170] - 57.5 - 77.1, Firewalker Ruins
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• [npc=72245] - 47.6 - 87.3, southeast of Old Pi'jiu
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• [npc=71919] - 37.4 - 77.4, center of Old Pi'jiu. Can be summoned by completing the Skunky Beer event.
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Normal rares have a 30-60 minute respawn time, rare elites have from half hour to half day or even more (check Golganarr). In addition, some rares require player interaction to spawn.

An addon comes to our aid, though it's outdated for a while, _NPCScan is still working. It notifies us if any rare mob is available in the range of our sight. We just need to add the mob's ID number we want to track. To do this, simply copy+paste the following lines one-by-one into the wow in-game chat while the addon is enabled -- or create a macro to batch.

/npcscan add 73174 Archiereus
/npcscan add 72775 Bufo
/npcscan add 73171 Champion
/npcscan add 72045 Chelon
/npcscan add 73175 Cinderfall
/npcscan add 73854 Cranegnasher
/npcscan add 73281 Dreadship
/npcscan add 73158 EGander
/npcscan add 73279 Evermaw
/npcscan add 73172 Flintlord
/npcscan add 73282 Garnia
/npcscan add 72970 Golgannar
/npcscan add 73161 Furyshell
/npcscan add 72909 Gu'chi
/npcscan add 73167 Huolon
/npcscan add 73163 ImpPython
/npcscan add 73160 Ironfur
/npcscan add 73169 Jakur
/npcscan add 72193 Karkanos
/npcscan add 73277 Leafmender
/npcscan add 73166 Spineclaw
/npcscan add 72048 Rattleskew
/npcscan add 73157 RockMoss
/npcscan add 71864 Spelurk
/npcscan add 72769 Jadefire
/npcscan add 73704 Stinkbraid
/npcscan add 72808 Tsavo'ka
/npcscan add 73173 Urdur
/npcscan add 73170 Osu
/npcscan add 72245 Zesqua
/npcscan add 71919 Zhu-Gon
/npcscan add 72032 Zvezdan
/npcscan add 73297 Dead crane

I added [npc=72032] to the list because that guy is the indication of [npc=72048]. Also added [npc=73297] as the indication of availability of [npc=73854]. As you can see I used abbrevs for names mainly because macro space issues. After all, you can type anything for names actually. _NPCScan scans for IDs and will print the original name of the mob despite the name you set in.

Although it's totally off-topic below, but it may be better to add everything worth-to-mention in 5.4 to _NPCScan list at once.
You probably know they changed the One Many Army's mob types in the Vale of Eternal Blossoms and these (now rare) mobs drop 5.4 cooking ingredients for the new 5.4 recipes, as well as [item=103624]. You can extend your _NPCScan list with them if you're interested in cooking:

/npcscan add 63978 Kri'chon
/npcscan add 63691 Huo-Shuang
/npcscan add 63509 Wulon
/npcscan add 62881 Gaohun
/npcscan add 58949 Bai-Jin
/npcscan add 58778 Aetha
/npcscan add 63101 Gen Temuja
/npcscan add 58768 Cracklefang
/npcscan add 58769 Vicejaw
/npcscan add 63240 Smaster Sydow
/npcscan add 58771 Quid
/npcscan add 63695 Baolai
/npcscan add 58474 Bloodtip
/npcscan add 62880 Gochao
/npcscan add 58817 Spirit of Lao-Fe
/npcscan add 63977 Vyraxxis

In addition, if you're interested in it you can add [npc=73293] the rare vendor of Timeless Isle aswell.

If anything is unclear about the usage of _NPCScan please visit their website for documentation.

Save yourself time and a lot of tabs in your browser.
The Wowhead Rare Elite Guide has maps, loot lists, and abilities for all the rare elites in this achievement and other elites across the Timeless Isle.

TomTom waypoints (one per rare):

/way Timeless Isle 50.2 22.9 Archiereus of Flame
/way Timeless Isle 34.8 31.2 Archiereus of Flame (summoned)
/way Timeless Isle 63.8 73.0 Bufo (patrols)
/way Timeless Isle 60.6 48.6 Champion of the Black Flame (patrols)
/way Timeless Isle 25.2 36.0 Chelon
/way Timeless Isle 54.4 53.2 Cinderfall
/way Timeless Isle 43.8 69.6 Cranegnasher
/way Timeless Isle 25.8 23.2 Dread Ship Vazuvius
/way Timeless Isle 31.0 49.2 Emerald Gander (Brilliant Windfeather)
/way Timeless Isle 72.8 84.8 Evermaw (patrols)
/way Timeless Isle 46.6 39.6 Flintlord Gairan
/way Timeless Isle 64.6 28.6 Garnia
/way Timeless Isle 61.6 64.0 Golganarr
/way Timeless Isle 24.6 57.6 Great Turtle Furyshell (Great Turtle)
/way Timeless Isle 40.6 79.6 Gu'chi the Swarmbringer (patrols)
/way Timeless Isle 68.2 59.0 Huolon (patrols)
/way Timeless Isle 34.2 73.4 Imperial Python (Death Adder)
/way Timeless Isle 29.8 45.6 Ironfur Steelhorn (Ironfur Great Bull)
/way Timeless Isle 53.6 83.0 Jakur of Ordon
/way Timeless Isle 33.8 85.8 Karkanos
/way Timeless Isle 67.6 44.0 Leafmender
/way Timeless Isle 22.8 32.4 Monstrous Spineclaw (Ancient Spineclaw)
/way Timeless Isle 60.6 87.8 Rattleskew
/way Timeless Isle 44.2 31.0 Rock Moss (in cave)
/way Timeless Isle 59.0 48.8 Spelurk
/way Timeless Isle 44.8 38.8 Spirit of Jadefire (in cave)
/way Timeless Isle 71.4 81.4 Stinkbraid
/way Timeless Isle 54.2 42.8 Tsavo'ka
/way Timeless Isle 44.2 26.6 Urdur the Cauterizer (patrols)
/way Timeless Isle 57.6 77.2 Watcher Osu
/way Timeless Isle 47.6 87.8 Zesqua
/way Timeless Isle 37.8 77.2 Zhu-Gon the Sour


_NPCScan add commands:

/npcscan add 73174 Archiereus of Flame
/npcscan add 73666 Archiereus of Flame (summoned)
/npcscan add 72775 Bufo
/npcscan add 72032 Captain Zvezdan
/npcscan add 73171 Champion of the Black Flame
/npcscan add 72045 Chelon
/npcscan add 73175 Cinderfall
/npcscan add 73854 Cranegnasher
/npcscan add 72049 Cranegnasher
/npcscan add 73281 Dread Ship Vazuvius
/npcscan add 73158 Emerald Gander
/npcscan add 73279 Evermaw
/npcscan add 73297 Fishgorged Crane
/npcscan add 73172 Flintlord Gairan
/npcscan add 73282 Garnia
/npcscan add 72970 Golganarr
/npcscan add 73161 Great Turtle Furyshell
/npcscan add 72909 Gu'chi the Swarmbringer
/npcscan add 73167 Huolon
/npcscan add 73163 Imperial Python
/npcscan add 73160 Ironfur Steelhorn
/npcscan add 73169 Jakur of Ordon
/npcscan add 72193 Karkanos
/npcscan add 73277 Leafmender
/npcscan add 73166 Monstrous Spineclaw
/npcscan add 72048 Rattleskew
/npcscan add 73157 Rock Moss
/npcscan add 71864 Spelurk
/npcscan add 72769 Spirit of Jadefire
/npcscan add 73704 Stinkbraid
/npcscan add 72808 Tsavo'ka
/npcscan add 73173 Urdur the Cauterizer
/npcscan add 73170 Watcher Osu
/npcscan add 72245 Zesqua
/npcscan add 71919 Zhu-Gon the Sour


You can add them all at once with the Paste addon.