Magic The Gathering: Arena Dev Tracker

Great description, thanks so much! That will really help us try to narrow down what went wrong here.

Thanks for the report!
QA's been trying to reproduce this, but can't get it to happen. Do you have any other details about what happened here so we can get closer? What exactly was happening as your opponent conceded in game 1? Where in game 2 did you get stuck? Do you think it's possible you disconnected anywhere in there?

Has anyone else had/not had this happen to them?

Yeah, that's pretty much it. Because of a bug (introduced by Gutter Grime), the sacrifice part of: Equipped creature gets +1/+1 and has “{W}, {T}, Sacrifice Citizen’s Crowbar: Destroy target artifact or enchantment.” Lost its reference to Citizen's Crowbar, and the rules engine decided it meant sacrifice All The Things.

The Arena rules backend works by basically reading the cards (natural language parsing), and we have to regularly adjust that reading process to make sure it understands new cards properly. In some cases, like this one, that can lead to older cards getting new (and improper) behaviors. We have a lot of automated and manual testing to check for this, but with ~8k cards there's always the possibility that something sneaks through.

In any case, we're working to get a fix out soon. Until then, I wouldn't recommend sacrificing Citizen's Crowbar (and your whole board).

Do you not have phones? Wait...

When you tap on the opponent's hand it opens a browser (like you were searching your library), and you pick from that.

I wouldn't say Intrepid Adversary is THAT related; all kinds of cards reference their own titles. Gutter Grime and Citizen's Crowbar are of a much rarer category of cards that self-reference in abilities they confer to other objects. Most times a self-reference simply means "the object that has this ability", but for Gutter Grime and Citizen's Crowbar, they actually mean "the object that conferred this ability". Note that such references need to work even if that object stops having that name. #wotc_staff

Sorry I didn't post here, y'all are still my favorite. #wotc_staff

Here. #wotc_staff

Mobile has a different interface for selecting opponent cards when casting Emrakul. Our data shows most mobile players are not ants, so the cards were too small to keep the desktop interface.

Update: This bug is now fixed.

There is a bug causing it to be ranked. We will be deploying a fix shortly.

Note that the bug does not affect matchmaking which is still record-based, but until the fix is made, the outcome of matches will change your rank.

Can you clarify your question? In a normal game situation, the way [[Nullhide Ferox]] works is: when either player has priority, that player sees the Ferox glowing, indicating you can activate it. You then click it, confirm that you want to activate it, then the ability goes on the stack.

Nothing in particular changes if you're in control of another player; you should probably be careful that you're making the correct player activate the ability. #wotc_staff

From our discussions with the rules management, both Companion and Venture into the Dungeon should work with player-control effects. #wotc_staff

Pretty good summary. I'll supplement a bit:

• Python is used for the offline process of parsing the cards. Its advantages are: access to the Natural Language Toolkit library, simplicity in input/output interfaces, and familiarity for most of the team.

• Our usage of CLIPS is akin to many games' usage of scripting languages like LUA: it is the primary environment in which content-specific code is run. Its main advantages are that expert systems are a good model for the vast interconnectedness of MTG rules and that it's a language that's very amenable to on-the-fly loading of code.

• C++ has more of a role in the rules engine than you give it credit for: I'd say it's the skeleton of our game, with CLIPS as its flesh. C++ manages the fundamentals of the game, such as its state machines; it manages message traffic to and from the client, including game state redaction and response validation; and yeah it handles performance and/or algorithmica...

No, not me. Some people from the team were, but I’ve never done MMOs.