One of the playtest cards from Gavin’s unknown event was a card that referenced the MOM legendary team up cards; and he said that the card didn’t really work within the rules. Although that is technically true, I find it hard to believe it could not be easily worked into the rules. Obviously it is clearly understood from the average player POV, but from a rules perspective, why couldn’t there just be a section in the rules that lists all the cards that are legal options? That already exists for Apocalypse Chime, City in a Bottle, and Golgothian Sylex; and I would argue they are far less intuitive or easy to remember when it comes to what cards they apply to. This isn’t me demanding that Gavin’s card be made legal, more so it’s me asking: why can’t cards like that get made? Cards/mechanics that reference a small and intuitive list of cards, with the comprehensive rules having a formal definition for that list?

It comes down to how much stress does it put on the system and is it worth that stress? We believe the answer is no, because it’s a lot of stress for minimal pay off. That’s why acorn/silver-border cards exist. There are things that are practically easy to use, but are onerous on the rules system. Those cards should exist because they’re fun, but we can do so without causing problems with the larger rules structure.

I would say that Apocalypse Chime, City in a Bottle and Golgothian Sylex were the first cards that used the concept of "batching". However, their batch is explicitly defined in the comprehensive rules (CR), and would be a little long to fit in reminder text. Would you ever make another "intuitive" batch where it can be roughly described in reminder text, but you might have to consult the CR in order to know 100% whether something is part of the batch?

Yes, if the batch was generally intuitive enough that players could guess at 99% of it.

Hey Mark! Are City in a Bottle/Golgothian Sylex/Apocalypse Chime effects still black border, or have they moved to silver border like World-Bottling Kit? If they are black border will we ever see this effect again?

Black border can no longer mechanically reference expansion symbols.

FWIW, Golgothan Sylex, Apocalypse Chime, etc can actually fit on the cards, it's just that it would require the internet to be at hand when played (Gatherer says, for example, "Destroy all nontoken permanents with a name originally printed in the Homelands expansion. They can't be regenerated.")

But it doesn’t really fit on the card when you have to look up the longer answer to know what the card does.

Powerlevel and playability sat aside are cards like Apocalypse Chime still doable in blackborder? Also do you make many judgecalls during Tuesday draft/sealed?

We’ve moved away from those type of effects as the expansion symbol is no longer something black border cards can care about.I’ve yet to be asked to make a judge call. There are a lot more qualified people in the Pit to ask rules questions.

What was the reasoning behind old-school set hosers like Apocalypse Chime?

We like to have safety valves in case something breaks. I think the idea was a set safety valve. Not one of our better ideas.

Has a card that hoses a particular set, like Apocalypse Chime or City in a Bottle, ever been considered by R&D since Homelands? (Other than City-Bottling Kit)

Yes, for Un-sets. (Unhinged had World-Bottling Kit.) No for black-bordered sets. Expansion symbols are no longer something cards can track.