Needs Stones and Doom.
Pointless for just one power, I’d drop him, or add Stones and Fortune so you can reroll cover saves on your Reapers.
Too many upgrades that you really don’t need. Drop the Exarch for more Dragons, or if you insist on the Exarch for the flamer. It will make this unit more capable of taking hordes if this is an ‘all comers’ list.
Too many upgrades on those Serpents. The only way I’d justify taking those would be if you had them on a Serpent that had Banshees and you wanted to do a 1st turn rush to get them in position. Stones and Chin Cannons are plenty.
With the points saved from this and the Dragons you should have enough to get a small Pathfinder squad to sit at home.
Not much to say here, but I’d consider this a Hail Mary unit as if it even survives long enough to reach an opponent you might get at least on attack in, kill one unit or light vehicle, then they’ll get shot up and break.
I would not use these, period. They look good on paper, but you just spent over 200 pts. on five models. 5 TEQ’s are cheaper than this and deadlier.
Too many upgrades on the vehicles. I’d consider taking EML on this so you can have more options for busting light armor, as with only two reliable TL BL your transports could end up doing double duty killing other tanks.
good hunting.