How do you make evident what your lands are or not? Is it hard to keep track of how many mana your opponent has open?
So far it hasn't been hard to track. Without being told to do so players seem to naturally play their "lands" in a seperate part of their battlefield.
For the most part it's not too hard to remember what people actually cast as a spell because those cards typically have an effect on the game that's going on, so you're pretty well aware when someone casts Nicol Bolas as opposed to playing it as land because you know it's something you have to deal with.
One other cool feature of Type 5 is that I've noticed: in a lot of games where I lost, the card i needed to win was sitting right there on the table as land. Deciding what cards to play as land makes for some interesting decisions.
It's also interesting that you can have lands that make you a TON of mana, but I might have to tap a couple of my lands to get the colored mana I need and then I'm tapped out and can't counter-spell anything. Nat (lochnivar) and I had a pretty cool game where he had Legacy Weapon in play but had to tap all of his lands to get the 5 colors of mana he needed to use it, which would prevent him from being able to do other things.
Now that I've played about 15-20 games of "Type 5" I've been thinking a lot about how to design the card pool. The Type 4 card pool works fine, but what if we were designing the pool with Type 5 in mind?
* Having a ton of Instants isn't as important in Type 5 and Sorceries don't have to be as good to make the cut.
* Artifacts are really good because they are very easy to cast (Planar Portal, Tower of Fortunes, and Kozilek seemed to be some of the most powerful cards).
* Split cards are very good because they make a lot of mana as lands but dont require a lot of mana to cast.
* Cards that cost all five colors of mana are some of the best land cards. I got a deck that had Menomic Nexus and Conflux, which was sweet because the Nexus let me actually cast Conflux.
* Firebreathing abilities can be pretty safe when they require colored mana. Fireballs are probably still a bit unfair, tho.
*Land destruction is pretty good.