The assault was unlawful. Your opponent can name a decide at any time, and is required to take action as quickly as he observed the error. The penalties of that error depend upon the foundations enforcement degree (REL) and the decide’s name. The unlawful assault will probably be reverted, however you’ll not be allowed to animate and untap a unique mountain at any REL.

In the Tournament Rules, it’s acknowledged that, amongst others, that

Players are answerable for:

• Maintaining a transparent and authorized recreation state.

• Calling consideration to any guidelines or coverage infraction they discover of their matches.

As you famous your self, the mountain you untapped and changed into a creature has summonig illness and can’t assault. Therefore you dedicated a recreation error.

As for penalties, given the circumstances you describe, a decide would most likely not come to the conclusion that you just have been making an attempt to cheat, since you had an equal, authorized play at your disposal. Therefore, a recreation loss or worse appears out of the query right here.

At common REL, similar to Friday Night Magic or pre-release tournaments, with comparatively minor prizes at stake, the decide would probably determine to rewind the sport state to earlier than your unlawful assault.

A participant makes an in-game error not talked about above

This will cowl the majority of participant errors, and normally the least disruptive choice is to go away the sport as it’s after fixing something that’s presently unlawful (e.g. an Aura enchanting an unlawful everlasting). If the error concerned a participant forgetting to attract or discard playing cards, have them carry out the suitable motion now. Otherwise, if the error was caught rapidly and rewinding is comparatively simple, it’s possible you’ll undo all of the actions again to the purpose that the unlawful motion occurred. [..]

Note that, since untapping the just lately performed mountain was completely authorized, you’ll most likely not be allowed to rewind that motion, additionally for academic functions:

Player training is a precedence; remind the gamers to play extra fastidiously, however keep away from being heavyhanded with a view to preserve your occasions enjoyable and relaxed. If a participant continues to repeat a mistake regardless of a number of reminders, it’s possible you’ll warn them that the following prevalence will end in a Game Loss.

Further penalties shouldn’t be anticipated. As you your self admit to taking part in sloppily, this looks as if a textbook case of an academic ruling.

At aggressive or skilled REL, the next rule applies:

2.5. Game Play Error — Game Rule Violation — Warning

Additional Remedy

First, take into account a easy backup (see part 1.4).

This would already be a treatment to repair the sport state, because the backup is trivial in your case.

You would obtain a Warning penalty for a Game Rule Violation infraction. Had your opponent not observed and reported the error inside a short while, he would have acquired a Warning for a Failure to Maintain Game State:

For most Game Play Errors not caught inside a time {that a} participant might fairly be anticipated to note, opponents obtain a Game Play Error — Failure to Maintain Game State penalty. [..]