I played Yu-Gi-Oh up until 2006. I really liked it and was in tournaments. I was kind of cheap though....
Jinzo/Royal Decree = Opponents can't activate trap cards
Horus Level 8 (easy to get out) = Opponents can only play magic cards under my own terms
Mystic Swordsman = LOL@YOUR FLIP CARDS! Get them out of here!
Black Luster Envoy of the Beginning = Take your monster and GTFO!
Cyberstein + Twin-header Cybernetic Dragon + Axe of Despair = 8000 life point kill in one turn (I can get this out on my first turn with a perfect hand IF I go second, and have done so many times)
I also had tons of other really good cards, and yes. I was a one deck kind of guy. It was a meta-game deck and people hated to play against me because I can, with fair ease, make it nearly impossible to get at me unless they out power my side of the field in terms of brute strength. Which can happen on some occasions. Mystic Swordsman is a little tricky to kill when I activate my trap card. xD
I played Magic for the past few years. From Innistrad and had to quit at Khans. I drafted almost every weekend and got addicted. I have some good decks. 4 + a commander deck. I would say my most prized card, by a long shot. Is my foil Lilliana of the Veil. I went ape**** when I pulled that in a draft.