I can see the Nightshade Sproutling and the Dread Hatchling; it's the Nightmare Whelpling I'm having problems with.
In Darkness, Healing Flame is not great, so you're probably forced into Nightmare in the third slot. But Nightmare's damage is not spectacular because of its heal-suppression, which is probably not needed in Darkness anyway, so it's not the star it might have been. Playing the odds, at 244 you'll more often be slower, so Tail Sweep in the first slot - that Dragonkin racial might just kick in at the perfect time.
Three Call Darkness are not so much OTT as wasteful. The Sproutling is not affected by weather, so you can keep the heal, and Lash and Blinding Poison pick themselves.
Start with the Dread, CD-NS, swap to Sprout, blind, get the heal up, stall, swap to Nightmare when you have taken some damage, and heal Sprout on the back line while the Nightmare puts up CD again. Probably let the Nightmare Tail Sweep until it dies, come in with the Dread and CD-NS again. Dread dies. Sweep with Sproutling. Something like that?
Depending on opposing team, ofc - I can certainly see that you might start with the Sproutling to play head games with a Valk or Kid, since the Blind is your only avoidance. I'm not sure how best to approach an Imp. He has to swap you out before your first NS; you've nerfed his healing but you don't have a second NS in the team to take advantage of the Darkness. (Oooh, oooh, I want a Dread Hatchling/Bone Serpent
) A Teroclaw will be faster than your Dread Hatchling and will be effectively Elemental. That's where your Nightmare Whelp might shine, starting against a Teroclaw, taking weak damage and being patient until the Dodge goes away.