The F2P way of clearing the DD tower 26-30 in just two tries (one try if you didn't brick!):
Floor 26
1st part - Generic Light beatstick deck
2nd part - Amazoness/Synchro BEWD
3rd part - Synchro BEWD (restart if you bricked!)
Floor 27
1st part - Amazoness + Warm Worms/Hiro
2nd part - Generic beatstick with more than 20 cards (don't destroy opponent monsters if you can, and stay defensive)
3rd part - Amazoness (really anything)
Floor 28
1st part - Reptile beatstick (this is the only one where I made a very "particular" deck, the deck needs the ff core: 1) Reptilianne Vaskii, 2) Worm Jetelikpse, and 3) Wall of D) Very tricky to finish and may need some retries!
2nd part - Any with Dian Keto or Supremacy Berry
3rd part - CA Saffira with Lava Golems
Floor 29
1st part - Amazoness (remove Tiger)
2nd part - Synchro BEWD
3rd part - Any defensive deck with 3x Worm Jetelikpse or Synchro BEWD (w/ 6-7 Tuners)
Floor 30
1st part - Amazoness
2nd part - Zombie Swarm (Gozuki + Il Blud + Call of Mummy core)
3rd part - Synchro BEWD
BOSS: Power Tool (Leo's skill) + Geargia
Eazy! Took me less than 5 hours!
How many deck could you possibly build in 1 f2p account? I actually made another account just to play treasure panda deck because I've calculated that if I made it in my main account I might not have any gems from characters left to strengthen the decks I already have.
Well, i've used ally of justice with 3 canadia and gravity blasters against the dragon deck and union deck, i never lost... Since all of the tower monster is light attributed, ally of justice does wonders, just let y'all know