Threshold

Threshold is an ability word that gives a card different or additional characteristics if its controller has seven or more cards in their graveyard. It was introduced in Odyssey and featured as a draft archetype for Rats in Bloomburrow.
==Description==
Threshold indicates that an additional or different ability is available if the controller of the card with threshold has seven or more cards in their graveyard. It is written in one of the following ways:
*Threshold — As long as there are seven or more cards in your graveyard, [static ability], [self-replacement], [activated ability] and/or [triggered ability]
*Threshold — [static ability], [self-replacement], [activated ability] and/or [triggered ability]. Activate this ability only if seven or more cards are in your graveyard
===History===
Threshold appeared as a keyword ability on 84 cards in the Odyssey block. However, rules-wise it wound up being a bizarrely complex characteristic-setting ability. “Threshold — [text]” meant “As long as you have seven or more cards in your graveyard, [this object] has ‘[text].’” The wording on it made it so that it could be active in the middle of combat damage, the middle of ability or spell resolution, and often immediately after paying discard or sacrifice costs and before the ability resolved. Conversely, it could also be turned off in the same way. Threshold was seen in all colors. However, in Odyssey and Torment, blue was notoriously good at putting cards into the graveyard, and therefore had fewer threshold cards (it would have had an unfair advantage over the other colors). 
It was later realized that Threshold actually was a precursor to ability words that were formally introduced with Saviors of Kamigawa. Ability words are so simple that they don’t actually have any rules meaning. The formal change was made with the release of Time Spiral. The “threshold” section from the rules was eliminated, and all threshold cards received errata. 
<c>Deep-Sea Terror</c> (Magic Origins), <c>Search for Azcanta</c> (Ixalan) and (Strixhaven: School of Mages) essentially feature the mechanic, but without the ability word. <c>Jace, Vryn's Prodigy</c> (Magic Origins), (Innistrad: Midnight Hunt) and <c>River Serpent</c> (Amonkhet) have a five-card version.
The mechanic made a reappearance in Modern Horizons on a reprint (<c>Nimble Mongoose</c>) and a new card (<c>Excavating Anurid</c>).
Threshold was one of the non-evergreen, non-deciduous ability words included in the Unfinity sticker sheets. It also appeared in Alchemy: Thunder Junction and some new reprints for Modern Horizons 3.
Mark Rosewater had stated that if Threshold would return to a premier set, it would likely be errata'd to work as Threshold N (allowing for an adjustable threshold). For a while Play Design preferred eight cards. Nonetheless, it reappeared in its original form in Bloomburrow. It appeared on seven creatures and was largely fueled by Surveil rather than discarding cards or sacrificing lands.
With the release of Foundations, threshold officially became deciduous.
====Related mechanics ====
Some creatures in Odyssey with threshold are lycanthropes, meaning they change from one thing into another; the creature type line captures the before and after, but the art only shows one, usually after.
Several related "threshold mechanics" like metalcraft also allow a card to swap between various states based on some external criteria somewhere in the game. Many other graveyard abilities like delirium, descend and spell mastery also take inspiration from threshold. 
<c>Jace's Phantasm</c> from Magic 2015 was the first card to have reverse threshold (caring about the number of cards in the opponents graveyard, albeit 10 instead of 7). Eight became the more common reverse threshold number, for both Zendikar Rising and March of the Machine.
==Rules==
==Rulings==
*Instants and sorceries with threshold check if seven or more cards are in your graveyard when they resolve, not when they're cast or put on the stack.
* Activated and triggered abilities that permanents have at threshold check the number of cards in your graveyard only when the abilities are activated or triggered. Even if you have fewer than seven cards in your graveyard when the ability resolves, it will still resolve normally.
*Static threshold abilities are simply "on" when you have seven or more cards in your graveyard and "off" when you don't.
==Examples==
==References==