five toughness makes it difficult to kill during combat if you want to rummage, and trample can become threatening very quickly if your Ring is at Level 4
Changing creature types on vehicles is intriguing, but Im not sure thats worth pursuing
While every deck can be edited to be successful as you gather more cards (some cards featured in the game are just hilarious), some Structure Decks are practically ready for competitive play immediately

July 26th 2020: Ghost Day 1 Dark Spirit of Malice 1 Dark Spirit of Banishment 1 Archfiend Empress 1 Curse Necrofear 1 Grinder Golem 1 Abominable Unchained Soul 1 Unchained Soul of Disaster 3 Unchained Twins Sarama 3 Unchained Twins Aruha 3 Graff, Malebranche of the Burning Abyss 1 Cir, Malebranche of the Burning Abyss 1 Scarm, Malebranche of the Burning Abyss 1 Barbar, Malebranche of the Burning Abyss 2 Tour Guide From the Underworld 1 Fiendish Rhino Warrior 1 Spirit Message I 1 Spirit Message L 1 Spirit Message N 1 Spirit Message A 3 Dark Spirits Mastery 2 Dark Sanctuary 3 Abominations Prison 1 Card Destruction 1 Destiny Board 3 Abominable Chamber of the Unchained 1 Call of the Archfiend 2 Unchained Soul of Rage 1 Unchained Abomination 2 Unchained Soul of Anguish 1 Cherubini, Ebon Angel of the Burning Abyss 2 Dante, Traveler of the Burning Abyss 1 Dante, Pilgrim of the Burning Abyss 1 Security Dragon 2 Linkuriboh 1 Akashic Magician 1 Mekk-Knight Crusadia Avramax 1 Knightmare Phoenix 3 Gogogo Ghost 1 Gogogo Golem 2 Gogogo Golem Golden Form 3 Gogogo Giant 1 Gogogo Gigas 2 Dodododwarf Gogogoglove 2 Utopic Onomatopoeia 3 Adamancipator Analyzer 1 Block Dragon 1 Giant Rex 1 Xyz Slidolphin 3 Summoner Monk 3 Onomatopaira 3 Onomatopickup 2 Gogogo Talisman 2 Miracle Rupture 1 Monster Reborn 1 Harpies Feather Duster 2 TA.I

It is by no means an optimal or finalized build, merely a starting point to serve as proof-of-concept
As an honorable mention in the land game, Dark Depths is a joy to witness