I saw this thread, recently and found it very interesting and wanted to add to it. I enjoy seeing others' house rules, as well as I wanted to share my own. I think it helps work out game details, as well as receive some constructive criticism on my own.
My wife and I play the game pretty regularly, always tweaking and learning things. In addition, I recently got my cousins and siblings into the game also.
Here's some of the house rules that we've all played with and enjoy.
1. An army may have between 600 and 625 (or 650, still tweaking that one) of army points. But, a maximum of 3 army cards. This last part was added cause my wife figured out a way to give Nahiri 4 army cards at 600 points, and was just wrecking shop, through attrition.
2. An army built below 600 points may put the remaining points into their Spell deck, allowing them to exceed 200 points.
3. Spell decks can be any quantity of cards, not exactly 12. But, may only have 1 copy of each. (Still toying with that last part.) Spell decks are still 200 pts, unless added to by Rule 2.
4. Hidden Enchants may be flipped at player's discretion. They declare if they want to flip it, once attacks have been declared, but before dice are rolled. If chosen not to be flipped, it is not discarded.
5. The Blazing Firecats may Haste with all 3. (Seems rough, but we've been playing that way this whole time and only just recently found out it was just 1 Firecat that may Haste.)
6. The Cryptoliths yield a height advantage of only 2, or always 1. Meaning, if A is on a cryptolith and B is on flat surface, A is +2. But, if B is on 2 sandtiles, A is +1. If B is on 3 sandtiles, A is +1. All the way up to 8. So, the Eldrazi Ruiner actually is equal to A. (There may be a ruling on the cryptoliths and would love to hear thoughts on this, cause we've yet to find anything. The way we interpreted the Cryptoliths, initially was a height advantage of 10, due to itself and the sandtile it's on.)
7. We don't use turn trackers, except when running the Ruiner scenario. Though, we are toying with a time limit of 1 hour for 1v1, and 1.5 to 2 hours for 2v2.
8. Engaged is only considered if A and B are adjacent AND one of them has initiated an attack.
9. Flyers may walk. (Got that from a thread on here. They said it was from Heroscape, and we tried the rule and liked it.)
10. Cards/abilities may not target "itself" unless clearly stated, basing intention. (ie. there is a
enchant planeswalker that give +1 attack to all figures within 4 clear sight spaces. Well, if a planeswalker is a figure, what other figures might there be, except creatures? None. So to give Chandra the ability to target herself with that enchantment seemed unintentional. A clearer example is Jace's Mind Stealer, which allows him to target a planeswalker within 4 clear sight spaces of Jace, and move, attack and use abilities, barring a d20 roll. Jace is a planeswalker, and is with 4 clear sight spaces of himself. Should he be allowed to mind steal himself? The wording seems that would be unintentional. On a freakish good role, Jace could mind steal himself over and over and just keep attacking, if these types of things were allowed.)
After that long winded Rule 10, my mind went blank of any others. Though, I think that's the bulk of them. Many of these don't seem to be game breaking. Most of them were used to handle when an ability or card wasn't clearly worded, or too ambiguous, or unintentional. We try to keep to the heart of the MtG card game, when it comes to rulings. Utilizing concepts such as the "stack" and "priority".
I'm interested at what you all might think of these. Or even if there is a rule that is already stated, that we might have missed.
Let's hope they keep coming out with more sets, cards, figures, and rules!