For basic AI stomping, all you need to do is use Yami or Kaiba, use their power that gives you their appropriate field spell, then fill your deck out with monsters with good attack that are buffed by the field spell. Add in up to three one-tribute monsters and focus on spells and traps that either buff your monsters or kill/destroy your opponent's stuff.
Don't use ritual monsters, fusions or anything that requires two tributes to summon.
(Relinquished is really good though - excellent value card that will pay for himself by stealing one monster)
Gems are best spent on Ultimate Destruction until you pull the excellent UR (Sphere Kuriboh) and SR cards (Shard of Greed, Order to Charge, that spell that kills traps and spells, Wonder Balloons...), then rotate to the water mini-box until you have that UR trap.
I blew lots of gems on the other box and regret it - stuff like Mirror Wall is nice, but that box will be around for a good few months yet and the first two boxes go away half way through next month.
I am hoping to build a deck based on how stupid Sphere Kuriboh, Bazoo the Soul Eater and Wonder Balloons are when working together.
