* They considered making Blood Aspirant one mana, but if it was going to hit Constructed, they'd rather it be a build around than something any red aggro deck would slot in.
* Tectonic Giant was a 4/4 that dealt 3 damage or temporarily drew a card, but only the first was being chosen. They made the draw stronger and weakened the first ability by making the creature 3/4, putting less pressure on being pure aggro.
* They wanted Phoenix of Ash to die and escape multiple times in a match, so they made it low cost. As a 2/2, players weren't bothering to kill it, so they gave it fire-breathing.
* Ox of Agonas was originally an uncommon (with weaker stats), but it turned heads, so they beefed it up and made it a mythic.
* Wolfwillow Haven could have activated its wolf ability at any time for Constructed, but they restricted it to your turn for Limited. It also sounds like they'll generally use "activate only on your turn" instead of "sorcery speed" in the future, since it's shorter.
* They had trouble making The Binding of the Titans interesting.
* Arasta of the Endless Web originally triggered on any noncreature spell, but they feared that would push it into every green deck, rather than as a solution against spell heavy decks.
* Haktos the Unscarred went from 2RW 5/1 -> RRWW 6/1 to prevent it from being combined with counterspells, even if they felt that deck was unlikely.
* The Titans originally had weaker stats but stronger ETB abilities. Kroxa destroyed a creature an opponent controls at random. However, that emphasized the ETB too much and not the big creature part.
* Shadowspear is them experimenting with equipment with normal activated abilities.
* Dream Trawler went through a lot of changes. The goal was a quick finisher for control decks, but not too quick. They find that quick finishers are better than slow grinds.
* Enigmatic Incarnation had a Birthing Pod style activation cost, but as they put more restrictions on the timing, they realized it could just be a triggered ability.