Regarding the hypothetical Ward costs that give opponents an upside instead of directly costing you anything, there's at least one card which does that repeatedly: Wall of Shards has an opponent of your choice gain life as a cumulative upkeep cost. This demonstrates that the game already treats benefiting your opponents as a cost.

Just because a card was printed once that does something doesn’t mean all problems with that thing were solved. Wards have to be costs and another player doing something isn’t a cost.

I feel like last strike can be solved by having a creature with an activated ability that can only be used when the creature dies, and only targets a creature that dealt it combat damage. Would this work?

There are wordy ways to roughly mimic it, but that’s not quite the same.

If/when: more cards with Substance?

If. Substance was created to solve a problem that we later solved better.

Some feedback: The reminder text on cases feels too vague to me. My interpretation was that they were automatically solved if you met the condition or at the beginning of your endstep, whichever came first. In my head, the flavor was you know the answer immediately (the special condition) or you spend time thinking about it (solved at endstep).

The fact that some people are confused by the Case templating has been passed along to the proper people.

I would like to note that I find it strange that it's been reiterated that design avoids mechanics that rely on memory and prefer to use counters and having new mechanics like "suspect" and "solve" release that require you to remember that the creature permanently has menace and can't block or that the enchantment is permanently "solved". It's very confusing to get information that this kind of design is bad and to be avoided and then to have it show up in a premier set twice.

When we have a set that has punch out counters as a memory aide, we allow some stuff we don’t in sets that don’t.

I keep thinking that the two word situation of the "Time Lord" creature type could have been solved by referring to them as "Gallifreyan."Gallifrey is/was the Doctor and Master's home planet, and not everyone from that world was a Time Lord or Lady.I know it's far too late to change it, but that's what I probably would have done.That being said, I just did a quick search, and it seems that canon for Doctor Who was a bit inconsistent from time to time, as it both said that "not every Gallifreyan is a Time Lord" and, numerous times, that the species name was "Time Lord."

As with any Universes Beyond product, we work with the licensee who is the expert on the property to make sure we’re using the correct terminology.

Would the problem of "Investigate" be solved by giving the other two popular tokens similar keywords, or would that be worse?

That makes the problem worse, not better.

"Creatures with no abilities can only be blocked by creatures with flying" / "Creatures with no abilities deal combat damage as if they had trample" - There! Solved it! Next problem? 😉

Rules have to be written so not only the rules work, but also so the players can comprehend what the rules are saying. An ability that grants an ability to a Vanilla creature, but technically it doesn’t, is not a recipe for success.

Would making Regeneration a triggered ability that when this creature dies: trigger if cost is paid, remove all damage and creature stays on the battlefield tapped? Wouldn't that have solved the flavor? Then the billion removal spells that prevent Regeneration would just keep the trigger from happening.

The fix is not as simple as it seems. If it were, we would have made the change.

For those of us out of the loop, what’s the issue as you see it with the Legend rule? Naively, any problems it causes can be solved by making the card not legendary.

Here’s the classic problem. I design a cool build-around card. Commander wants it to be legendary because it wants it to be the commander. 4-of formats want it to not be legendary, so you can play multiples and not draw dead cards.