Playing today and Ob Nixilis, Unshackled came out (again) to general groans around the table. One player in particular got quite salty saying that the game devolved into who can top-deck answers or take the hit, generally the decks that leveraged card draw and/or life-gain, thus control decks, the ones who were least incentivised to actually get rid of the Ob Nixilis. As the “fair” elf deck, he was already getting all the incidental hate, boardwipes and having to face bigger monsters than he was playing.

I mentioned that he was annoying to play against but he was one of my favourite cards to see in the format because he didn’t stop you doing what you wanted to do, just put a very high premium on doing it. Cards like Void Winnower, Iona, Gaddock Teeg very clearly shut off particular cards, actions or colours but something like Ruric Thar, the Unbowed or Ob Nixilis, Unshackled say you can do what you want, just that you have to pay the price.

I enjoy the mental "risk/reward" calculation everyone goes through to work these cards into their plans (or their plans around these cards). "Do I take the hit to get/play something that helps me but doesn't get rid of Ob/Ruric or do I get a card to kill them so I can play without them touching me and how much does each route that help my opponents? More or less than me?"

What are your pet cards that make the game a puzzle to be solved?

Nothing wrong with Ob Nixilis, Unshackled, as long as you play nice and don't pair it with Maralen of the Mornsong Sure, each player can go and fetch a kill spell, but do you want to lose 13 and let the rest of the table off the hook? Hell no, when I bleed, everybody bleeds!

I love cards like that, forcing opponents to make choices. Fatespinner and Split Decision are auto includes in blue, Volcanic Offering is nice, Chain cycle is always interesting, especially Chain of Acid is fun. Sometimes it kills a single permanent, sometimes it actually chains anger and spite until the entire field is decimated.

I do seem to be the only one enjoying Ob Nixilis or Ruric Thar in our group. Table tends to gang up on me when I bring a Thar deck, some how I can't even convince a Maelstrom Wanderer player with max. 10 nonland, noncreature cards in his deck that he'll better leave it to the spellslinger or Artifact players to handle Thar.

I like playing against "puzzle cards." I don't even mind Void Winnower (although Iona takes it too far.)

I know a lot of people hate it, but I love Possibility Storm.

My pet card is Illicit Auction. In Neheb it gets better because you either get what you're bidding on or get a bunch of mana.

Perplexing Chimera

Some of my group dont like it, but I love it. It really does become a puzzle to solve, even for me! I have screwed myself up with my own chimera on more than one occasion.

I like Ob Nixilis, Unshackled because I think Commander can sometimes be a little too reliant on tutors to begin with. I've got some tutors in a few of my decks, but with the exception of my Gitrog Monster deck (which searches for land a lot) I don't really rely on them a whole lot. It's handy to have the option of going to grab something to fit a situation at times, but tutoring out the same combo pieces to win in the same way every single game kinda goes against the spirit of EDH, imo - it's singleton for a reason.

It's hard to say what my favorite cards in the format are, outside of cards I just like a lot because they're really good in a deck I run, but I do find that wheel effects can often make games a lot more fun and interesting, particularly symmetrical wheels. Suddenly everyone's got a lot of new ammunition to work with, and the next turn or two is usually very interesting.

While they aren't for every deck or game, I generally enjoy:

Mana Cache - Lots of interesting choices. Keep mana back for answers and risk "giving" mana to the opponent. Tap out, even with nothing to cast, and potentially waste mana to prevent giving mana away

Storm Cauldron - More choices, but this time its what you need now vs. what you can "save" for later.

Teferi's Puzzle Box - This one is all about variety. Some people hate it because they can't "plan," but I find it interesting when you have to adapt each turn's new hand.

Teferi's Realm - Usually interesting in the way things phase in and out around the table. Though, often, one payer will just keep picking enchantment over and over to try keeping the realm phased out. Where's the fun in that?

Gravity Well - For something so simple, it's funny how many player's plans are thwarted when they can't attack with flying. Can often change combat dynamics in weird was.

Phyrexian Splicer - Another sleeper that seems simple on the surface, but the possibilities with mix and match abilities make combat math so fun. Note: Neither the creature losing nor gaining the ability have to belong to you...