Sound team. Suggest move Soothsayer into second place as (1) if it dies, you still have Valk and Mab together and (2) protect Valk from enemy EKs.
This one doesn't work, for me. The Rock Worms are mana blocked by the (expensive) Great Maw - and if Maw casts, you want to be getting skulls and using its giant attack, not pinging away with worms at the last enemy. Your other Maw team is heading in the right direction.
Sounds promising - but Dragon Soul is the MVP by far, don't put it in first place to die. There are also a lot of Dragons to choose from, may have something better than Dimetraxia? I'd suggest Dragotaur. Or Celestasia or Borealis if you are lucky enough to get one. Venbarak is a good pick - get his Magic Link trait to fill up TDS even faster. Btw the recent Krystenax is the best dragon to get for your Dragon Soul team, look out for him. Sheggra probably isn't: confuses your win condition.
Also: worth looking at dropping one dragon and putting EK on the front: EK/Sylvanimora/TDS/Venbarak would work well. EK is awesome, esp if you get some traits - no harm losing a little damage off TDS to put a solid EK on the front of the team. Keep the Abyssal banner though, charging TDS is still priority.
Maw/Borer/Sheggra is heading the right way. Pick something green that can get you some board control: Soothsayer is nice - Siren would be another fun option (shoot something brown to put browns on the board for Maw/Sheggra).