Wow! Thanks for letting me know about that debate - that was a good one! I just went there and posted the detail below. For better or worse, its the truth!
I would greatly appreciate your comments or feedback.
Hello Everyone, Great debate!
Casting an enchantment spell is considered casting a spell and is handled similar to other spell castings.
STEP 1: CAST SPELL
The caster will need to use a quick action, or his quickcast action to cast it, just like any other quick spell. The caster then checks the target to be sure it is legal, and also checks to be sure it is in range (up to 2 zones) and in LoS. If all are correct, he then pays the costs for casting the spell, which will include 2 mana since it is always cast face-down (hidden).
STEP 2: COUNTER SPELL
Players have a chance to reveal enchantments or use abilities which might counter the casting of the enchantment. For example, a NULLIFY could be revealed at this time.
STEP 3: RESOLVE SPELL
Place the face down enchantment on the target. Now it is in play. After the end of this step, and casting action, it can also now be revealed if the controller wishes.
We certainly understand the difficulty of managing hidden enchantments without your opponent being able to verify the legality of the target. We felt it was a "necessary evil" in order to allow for hidden enchantments. Hidden enchantments just add so much fun and tactics to the game! We had tried modified systems, and nothing provided as much fun and tactics as the current system, and we decided it was best for the game.
Some of you may disagree with that choice, and we respect your opinion. There are several on our team that would agree with you! It was a tough call.
In our design process we leaned heavily towards fun, realism, and flavor above all else. In some cases that makes the game less ideal for competitive tournament play, and it was a sacrifice we were willing to make in order to retain that fun, realism, and flavor.
Fortunately, all enchantments are quick spells, have a range of 2 zones, and require LoS to the target, so at least that much can be verified. If later it is discovered that the enchantment is on an invalid target it is immediately destroyed without effect. In casual play, among friends, that should only occur as unintentional human error.
I am curious, for tournaments, what you would want the penalty to be for revealing an enchantment on an illegal target? Since that could be a cheater, it may need to mean they lose the game. A separate rules team is working on tournament rules right now. Please share your thoughts on this. We appreciate everyone's feedback and always take it seriously!
Thanks everyone for the support!