I'd use Sniper Shot with that build. That would get the team to the debuff cap with Sniper Shot, and -45% ATK/DEF without (using Mordred). It'd work until pulling Frost Raphael from the 3rd Miracle ticket, after which Mordred is no longer necessary.
For Wind, after the same 2 Miracle tickets I could have:
Gaia, Sol, Titania, Hastur, Mordred (EX: Sniper Shot): -40% ATK/DEF
or
Gaia, Sol, Oberon, Hastur, Mordred (EX: Sniper Shot): -50%/-40% ATK/DEF
or
Gaia, Sol, SR Cybele, Hastur, Mordred (EX: ATK down) or Joan (EX: Black Propaganda): -50%/-40% ATK/DEF
After 3 Miracle tickets I could have the same as above, but with SSR Cybele, and if I'm willing to make do with -40% ATK, I can use Shingen for more damage or Mordred with any EX ability needed.
They're both balanced, debuff-reliant builds that trade damage for resilience. I suppose the Water build has a slight edge after 3 Miracle Tickets because it can get more DEF down and prevent overdrives rather than just mitigate them.