Baby Dragon in back slot is fine for now. Visk’s damage output is generally awful for the amount of mana he costs, but his base stats are higher. However, most of the time you wont cast or even try for mana on whatever is in this slot anyways, which is why I say Visk and Baby Dragon are pretty much interchangable here. Baby Dragon can occasionally get you a much better troop by transforming, but generally just gets off the one tiny bit of damage before becoming something that isn’t red, making him a useless back tank again since every other color is mana blocked.
I was using Wight because Wight does true damage, gains life, generates purple (which the rogue can hit for more damage), generates souls, and still covers red. His traits and spell are also perfect for surviving alongside the rest of the dragons since he doesn’t get buffed, and he has a Water Link to fuel Rogue faster and maybe even getting himself mana. Using 3 dragon/dragon claw troops will significantly lower your collective bonus over using a 4/4 team, but Wight is actually worth casting if you happen to get mana on him (which usually happens once or twice).
I don’t think Celestasia really improves the team much since she blocks Rogue from taking blue, but if you get to the point where she fills incidentally you can use her to buff the life and increase your surviability. Mainly I was thinking her only because of her higher base stats (because she is a legendary), and higher base max level (because she is a legendary), which can add up. I prefer eggs because it gives more team bonuses, doesn’t block mana. She will also slightly lower your collective bonus, because you’ll have one less dragon’s claw troop in the team, so you’ll have four dragons and three dragon’s claw troops. Same with using Emperina in the back slot.
Overall, I prefer eggs/dragotaur/d.rogue/Wight, after I leveled my magic bonus kingdoms to 10, for the reasons stated above. Super early, though, the bonus from either using Visk or Baby Dragon outweighed that, so until then, you might want to stick with one of them. I don’t think Wight is worth using unless you can get about 8-10 souls per cast out of him, really (which should also be enough to one-shot the weakest troop on several early PvP battles). Before then, stick with Baby Dragon.
You don’t need many levels on eggs, just enough to stall out early skull hits and get your team going. With Dragotaur and Rogue, you just need enough levels to survive, then mainly magic, which Drago gets at level 10 and 15, and rogue gets at 5, 10, 15, and 17, although most of rogue’s damage coming from the boost ratio from destroyed purples. Baby Dragon (and Visk) are fillers, you can avoid leveling them much if at all (mine was 5 when I dropped them, my eggs are still level 6, which is high enough to take a skull hit, which is all I need). I unlocked all the “bond” traits on the first trio just for survival purposes when I could as well (baby d./visk don’t need any traits for this team).
If/when you use Wight, you’ll want him at least as high level as the others as he can generate souls which you can use to level the others - though again, this is less important before you finish leveling your magic kingdoms so you can get an actually usable amount of souls per cast. Water link is also great, but every one of his traits is useful, if you can afford them.