I didn't have the Nexus Whelpling and my Stormborne wasn't leveled.
Nether Faerie Dragon 2/2/1 S/S (don't know if breed matters)
Lil' Tarecgosa 2/1/1
-Arcane Blast -- Nether Faerie Dragon dies
-Surge of Power -- Lil' Tarecgosa dies
-Surge of Power
used Nexus Whelpling, Chrominius, Lil' Tarecgosa
Nexus : Arcane Storm , Mana Surge
Chromisius : Bite , Howl, Surge of power
Lil' Tarecgosa : Arcane Blast , done (if needed you can always do Surge of Power to finish
Stormborne Whelpling: 1 - Call Lightning
2 - Thunderbolt
3 - Tail Sweep. Stormborne Whelpling can die here. In this case just proceed with Wild Jade Hatchling.
4 - Tail Sweep
5 - pass, Stormborne Whelpling dies
Worked the first time. Always the leveler, I brought in a L21 Wild Golden Hatchling (he was my highest non-25 Dragon), and he finished the battle with Ruinhoof at 34 HP. Neither one of my L25s got in Tail Sweep. They were both killed following their third Mana Surge. Worked out anyway. Thanks for the strategy Lazey & Xu-Fu.
This worked for me:
Nexus Whelp 1/2/2 + Lil' Tarecgosa 2/1/1 + Azure Whelpling 2/1/1
Arcane Storm > Mana Surge > Pass (going to die here no matter what move you use). > Bring in lil Tarec > Arcane Storm > Surge of Power > Tarec dies, bring in Azure whelpling > Surge of Power. Win. :)
Mechanical Pandaren Dragonling (1,1,2) was amazing! Cast Bombing Run followed by Decoy, then Breath until Bombing Run is off cooldown, rinse and repeat. Used Nexus Whelpling and Stormborne Whepling as suggested in main strat for slots 2 and 3.