Thaegen the Confined reworked to Thaegen the Confined. I'd like him to focus on building towards his ultimate, but his older versions would just alternate first and second abilities.
Brillia of Quirion changed to Brillia of Quirion. Her old ultimate didn't really work with mana pool rules, as the bonus would wear off and creatures would die after combat when you wouldn't expect. I could have made the old emblem wordier to get around that, but I opted to hammer home the "different land names" aspect of her.
Ainsleigh of Corru River completely reworked to Ainsleigh of Corru River. Her new design is meant to evoke priests of Innistrad such as Avacynian Priest and Sigardian Priest, as well as cards like Dearly Departed.
Lykarev the Usurper reworked to Lykarev the Usurper. The new Contender designs (which started around version 16) work better when they have something to do on a blank board. I still want Lykarev to have fairly mild abilities, since he's a 2CMC planeswalker, but I want him to have a better chance against decks with lots of spot removal.
Peng Ping, the Curious changed Peng Ping, the Curious. Increased his casting cost by 1 and changed the "play" requirement to a "cast" requirement. Peng Ping has been a big hit but he was a little too easy to just cast without using his ability. Since his abilities are so super powerful, I raised the bar.
Psommegos, Dekatia’s Dean reworked to Psommegos, Dekatia’s Dean. His old +X ability was more interesting in the pre-Contenders era, but now it's just kinda bad. His other two abilities were generic UB gold cards. Now, he's a graveyard-and-spells Contender, which fits well into the set's overall structure.
Raevel, Eternal Gardener tweaked to Raevel, Eternal Gardener. Her new -4 should be a solid ability that trades a fairly large amount of resources (four loyalty and a large token) for versatile, black-feeling removal.
Zaina Shreen changed Zaina Shreen. Her swap ability was too confusing for players. The new -2 should also better interact with Zaina-style decks, which typically contain a half-and-half mixture of small sacrificial creatures and large "payoff" creatures for her to +1 into. The -2 will let her get some value out of those smaller creatures while also giving her an answer to large creatures on the opponent's side.