Why do you have to "name a card type" ? Isn't the syntax simpler if you just say, "search their libraries for any number of cards with the same card type and total converted mana cost X" ? All your wording does is let players find out, in turn order, what other players are going to search for before they decide what to search for; do you think this will change someone's choice often enough to use the awkward wording?
I wanted to make the choice for the second player somewhat based on the choice of the first player. Essentially player 1 will have a deck built to take best advantage of this card. Player 2 has the advantage of not paying X, still searching for cards and knowing before he makes his choice what player 1 has chosen.
Imagine in Vintage playing first and choosing artifact at 0? You play all of your 0cc Artifacts and finish by dropping Chalice at 0. This is why the card's own CMC can't really be 3 or less. It's too easy to go: Land, Ritual (or Workshop/Lotus) Gateway, Artifacts for 0, cast some, Tendrils possible adding a Yawg Will in there for good measure.
Knowing what your opponent is calling and for how much may influence your choice.
Shouldn't this include a non-land clause? Otherwise it will filter all lands for a zero mana activation...
A very nice idea btw...
As far as I understand, since land cards have no casting cost they can't be searched for under wordings which refer to a CMC. I'll make these 2 changes in the first post anyway. Thanks!