Fourthly, in Mtg, Mystic Decree is an 'Enchant World,' a card type where only one of the TYPE can be in play ... which makes sense for the Terrain cards. If the opponent (or even you ...) play a different Terrain it should wipe out the one in play already. after all Tunnels in a Treetop Village on Contested Bridges in a Volcano would be just TOO insane!!
This is also how field spell cards work in Yu-Gi-Oh
But not how they work in EtG. See Flooding during an Eclipse.
Exactly. This is why I'm saying a special permanent type or slot would be useful here. That way it is guaranteed that there will be no more than 2 types in play at once and no more than one per player.
I do not think we need a special slot. Few terrain actually prohibit other terrain being nearby. Oceans and deserts are adjacent IRL. Furthermore even if B cannot exist with A or C that does not imply that A cannot exist with C.
In my opinion EtG has a better system than YuGiOh
If people want it so, I can pull out he single slot part.
As a final note though, the slot mechanic also adds in a balancing mechanism that is intended to make designing these a little easier.
E.g. balancing will be a little easier since no more than 2 scenery cards would be able to interact at once. Much like a player may not have two different shield effects going simultaneously.
Regardless of the slot mechanic, though, I would like to keep the integrity portion. Terrain should be more difficult to destroy than an object like a shield or weapon, but should be susceptible to earthquakes and similar earth based effecs. Thats how I see it anyway.
