Hello mark, I'm looking at urza's cave, and wondering why wasn't cavern of souls corrected to be a cave?

We chose not to errata old cards.

Hi Mark, i was talking to a friend the other day about this blog and he was amaze by the whole thing. He also asked me, did anyone ever asked him about why it took them so long to give Urza (ignoring Blind seer) and Yawgmoth cards?
As always, thanks for your time and all your hard work!

We didn’t have a way to capture planeswalkers as a card until we made the planeswalker card type, and by then Urza was long dead and out of the story. Luckily, we eventually did a set that went back in time and allowed us to capture him as a planeswalker.

Today is my thirtieth birthday. To celebrate the milestone, may I have a piece of obscure trivia about either Magic’s thirtieth planeswalker type, Ugin, or Magic’s thirtieth set (counting Limited Edition as a single entry), Urza’s Destiny? Thank you for everything you and your team continue to do for the game and community.

Urza’s Destiny was the one expansion where I was the sole design team. It premiered the flicker ability which was inspired by self-phasing, but triggering ETB effects. I originally designed a vertical cycle in white, but it got cut down to a single rare (with the ability closest to my common design).

Invoking the sacred rite of birthday trivia, do you have any trivia about Cauldron Dance? It's always been my favorite reanimation spell.

One of the things I enjoy is taking two effects that reflect one another on some vector. I had made Sneak Attack in Urza’s Saga and numerous one shot reanimation spells. I realized if I made the Sneak Attack effect return to hand at end of turn instead of sacrificing it, the two effects would put a creature from that zone on the battlefield with haste and then, at end of turn, return them to the zone it came from.Happy Birthday!

If/when "Erase (Not the Urza's Legacy One) (Not The Unhinged One)"

It requires another Un-set.

I liked Mercadian Masques but perhaps its downfall is not the set itself, but the fact it came after the infamous Urza block. This meant 1.) the players compared power level 2.) the designers were especially cautious to limit power levelSo the set was good, but had external forces leading to poor sales. I would like to revisit Mercadia, now with new technology/design tools without the external forces. Pretty please?

I would argue the set had some additional design missteps. When we ask players worlds they want to return to, Mercadia scores pretty low.

Any plans for future Urza Lands?

I don’t talk of future plans. It is a high bar to clear.

I hereby invoke the ancient rite of Birthday Trivia:What’s a cute bit of trivia regarding an obscure creature type you really enjoy?

The origin of Beebles is interesting. Artist Jeff Mirancola drew a Duelist cover of Squee. On it, he was swarmed by these little pink creatures. I found them cute, so when I was doing the card concepting for Urza’s Legacy (the creative team all left, so while we were looking for new people, I handled the creative duties) I put one on a card. After I did a second one, the brand team, at the time, asked us to stop as they were deemed too silly. So, I started putting them into Un-sets. My current goal is to get them back into premier sets. Happy Birthday!

Hiya Mark! It was my birthday a couple days ago, I wanted to ask you some trivia about the Carthalion cards (Jared/Jenson/Carth the Lion) or, failing that, something about my favorite color combination, GUR! Have a magical day! :D

Jared Carthalion is one of only two five color planeswalkers. That had been a request from the players for a long while, so I made Urza, Academy Headmaster in Unstable. The players then asked for an eternal legal one and that ended up being Jared Carthalion in a Dominaria United Commander deck. My gut is we’ll make another one one day (five-color planeswalker, that is).Happy Belated Birthday!

Is it a coincidence that the activated ability to meld Urza, Lord Protector costs seven mana, the same amount of mana produced by the Urza tron lands, or was that done on purpose?

I wouldn’t call it an “coincidence”. : )