I built a Type 4 Cube in 2007-8 as a way to teach my high school students how to play Magic without having to carry a bunch of lands and decks around with me (I had a few decks stolen back then, much easier to just have a cube), It was about 450 cards and super fun to play. I decided a few weeks ago to give the format another go and wow, has the power creep made building something playable more of a challenge than before. I also wanted this to be an even more portable format than before, so I can bring the whole thing in a small, self-contained box and decided something along the lines of 200 cards would work.

Counterspells are just as important as ever, but the alternate casting stuff has really improved over the years to the point that some of it is probably even too broken.

Type 4 basics: unlimited mana of all types at all times. One spell per turn, plus one "extra" spell using an alternative cost (Adventure, Overload, Morph, Dash, Cleave, etc) and as much cycling, channel etc as you want. 5 card hand size, 20 life. Communal library, individual graveyards.

Oh and the 200th card is the Gavin Verhey playtest card "Call Up Emrakul to Help," and I have the best token ever for that.