We have agreed that all cards are legal, and to add to that its also 2 headed giant, so it will be quite interesting. We still are going to follow the official rules however, just not the formats. That is why Im checking to make sure that those dont break any rules.
I am currently working on a deck without a format, and I was looking at Conspiracy cards. I know they are banned in all sanctioned formats, but if you could use any card you wanted in a deck, would you be able to use Conspiracy cards? I would think so because they are available for use and from what I've seen as long as they are in your "card pool" they can be used at the beginning of the game, but Im not sure.
I am building an emerge deck and it has a lot of creatures with "when you cast" effects like Elder Deep-Fiend. My question is when I cast something like elder deep fiend can you respond to it with an instant before I get to tap 4 permanents? And if you can and it is a counterspell, would the effect still resolve?
Example of a Conspiracy: Backup Plan