I like the random stuff that can pop up in this game and oddball ideas. Getting a deck to work that by all accounts shouldn't. I always dodge the common killer combo's or obvious theme decks and even if I use an oft played theme I try something different with it (my goblin deck works around gobbos with disadvantages and sacrifice abilities coupled with Death Spark and Goblin Grenade for example).
My Troll deck (there's only about 7 Trolls released in all sets of Magic, no lords, just trolls and an assortment of red/green burn and boost) is my fave, but I've really got to rebuild that one, it's not up to par anymore. One thing that I didn't realise when I originally built the deck is that all trolls have regeneration, which makes for some interesting tactics (the synergy of regen and Close Quarters is surprisingly powerful).
And secondly there's the deck I created for an Elder Dragon Highlander tourney that surprised me by actually doing something useful. EDH is a format where you create a 100 card deck with no more than 1 card of the same name (ie. all cards are restricted) and you have to choose a general who is a legendary creature and dictates what the possible mana symbols on any cards you use may be (this includes kicker or actiation-costs and the like). My deck is white/green/blue with Pheldagriff at the helm.
Nevins:
They quickly found out Indestructible completely skewed the balance of the game, so its only in one set (Darksteel) and never returned. A number of older cards actually became doubly useful when they cooked that one up (Carionette, Oubliette, Swords to Plowshares, Exile, Cannibalize, etc.). Even in Darksteel itself there were too few remove from the game cards to handle a Darksteel Collossus deck properly.
The all time killer cards still remain the ones of old (you can still put a Hypnotic Specter on the table and feel the anger flooding over you), but it seems like all races have become rather much like slivers in the way they share abilities and are synergetic in all kinds of ways. There's also loads of life link critters these days, which annoys the crap out of me, you used to have seperate cards to want some lifegain, now you can just put a 2/2 lifelink critter on the table for 2 mana.
)-Legions-Scourge. 
