Zephrys the Great is probably the most interesting card in Hearthstone History. This card look at the handsize, the amount of cards in each deck, the health, the classes and at the board. In this article we will focus on how he values enemy Deathrattles. If you want to learn how you manipulate Zephrys The Great to offer you the true ‘perfect’ card, this article might be worth a read.

In the Patch 16.0 Zephyrs got many improvments:

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Zephrys improvements

• Fixed a bug where minions with both Stealth and Taunt (such as Wardruid Loti) weren’t properly accounted for.
• Fixed a bug where weapons would sometimes be offered as a removal option against Stealthed minions.
• Druid Choose One cards now account for having the ‘Choose Both’ effect
• Fixed a bug where Starfall could be offered as removal against a single minion.
• Fixed a bug where Earth Shock was incorrectly offered as removal against targets that were reduced to 1 health by Shrink Ray or Equality.
• Adjusted how Zephrys values enemy Deathrattles.
• Fixed a bug with lethal calculations including Rush minions not eligible to attack heroes.
• Fixed several bugs involving certain cards not being offered:
  • King Krush
  • Faceless Manipulator
  • Shadow Madness
  • Doomhammer

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Players have posted they got less Silence offers after this patch, thinking it might be a bug. Senior Game Designer Celestalon added more info to the patch notes, showing us what exactly changed.

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I can add some more clarity to that patch note.

Previously, Zephrys valued Deathrattles as summoning a minion with stats equal to the difference in stats between the minion’s base stats and the expected stats of a vanilla minion at that mana cost.

Now, instead of evaluating it as summoning a minion, it does something more generic, of adding ‘that much value’ to the opponent’s board. In practice, this produces about the same results, except without the occasional card offered to deal with that extra summoned minion (which doesn’t exist).

This was pretty hard to explain in a succinct patch note (how many times did you have to reread the above two paragraphs and scratch your head?), so we opted to just say that “something changed with Deathrattles”, and leave it to skilled players to retrain their expectations around Deathrattles.

As for why Zephyrs “doesn’t like” Silence anymore… I don’t believe that anything has changed with Zephrys; rather the use cases that you’re using Zephrys in have changed. A really good example of this is Necrium Apothecary. I often get reports of Zephrys not offering Silence for Necrium Apothecary… That’s not a bug. That’s Zephrys working correctly, with the info he has. From his perspective, he sees a (4) 2/5 that had some Combo/Battlecry, and somehow gained a Deathrattle that it didn’t start with. That’s a not-particularly-threatening minion, and has some best-guess-probably-not-particularly-threatening Deathrattle. In other words, it’s about the same as a Gnomish Inventor that got Soul of the Forest’d. You and I know that that Apothecary is gunna Deathrattle into something much more impactful like a 7/7 or a +3/+3 handbuff, because we know what deck they’re playing and what to expect. But Zephrys doesn’t know any of that, and so (correctly, from his view) likely doesn’t offer Silence.

Source [/bluepost]

On a comment by Grandmaster BoarControl saying “if there were to be a busted deathrattle minion that had close to vanilla stats but offered huge value it wouldn’t offer silence” Celestalon answered

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[Source] No, it should not; we don’t teach Zephrys about individual cards, and he performs consistently, which you can use as skill. And we certainly wouldn’t want to tune Zephrys around extreme outliers.

[Source] The concept is that if the minion has a Deathrattle (and nothing else), that is likely where its “missing value” is. Yes, I simplified this a bit; it’s a bit higher than just subtracting the stats. [/bluepost]

Summary:

Before the Patch: Zephrys valued Deathrattles as summoning a minion with stats equal to the difference in stats between the minion’s base stats and the expected stats of a vanilla minion at that mana cost.

After the Patch: Now, instead of evaluating it as summoning a minion, it does something more generic, of adding ‘that much value’ to the opponent’s board. In practice, this produces about the same results, except without the occasional card offered to deal with that extra summoned minion (which doesn’t exist).