Here are the MTG Arena 1.07 April 23 patch notes

Wizards of the Coast made several adjustments to MTG Arena today following the release of Ikoria: Lair of Behemoths last week. 

An adjustment to matchmaking and the opening hand algorithm was included in the 1.07 MTG Arena patch today, along with several bug fixes tied to new IKO cards. 

IKO Premier Draft

Matchmaking has been somewhat off in Premier Draft over the last week with players getting paired with others who were higher or lower in rank. An adjustment to the matchmaking process should alleviate this issue. 

Players were also getting some odd opening hands when competing in the Premier Draft. This was because the algorithm was using a previous best-of-three formula. 

“We intend for best-of-one formats to use a modified opening-hand algorithm which pulls multiple potential opening hands and chooses one; Premier Draft was operating contrary to that, and we have fixed it accordingly,” WotC said. “To stave off any conspiracy theories, it was previously using our best-of-three opening hand rules (which pulls one, and only one opening hand).”

Bug fixes

Several cards within the IKO set were bugging out, from Lurrus of the Dream-Den to Zirda, the Dawnwaker. A couple of Mutate creatures were experiencing interaction issues, too. Most of the problems were resolved in the 1.07 MTG Arena update.   

• Sideboarding a designated Companion into your mainboard during best-of-three matches should now function correctly. 
• Lurrus of the Dream-Den now correctly handles X values in converted mana costs (For spells with X in their mana costs, use the value chosen for X to determine the spell’s converted mana cost. 
• Jubilant Skybonder’s cost increase now functions correctly when there are multiple instances of this card on the battlefield.
• Players can now appropriately select cards from their graveyard with Mausoleum Secrets.
• Setting Zirda, the Dawnwaker as your Companion will no longer cause the game to crash if you have cards with the Ascend keyword ability in your deck.
• Mythos of Brokkos should no longer bring back non-permanents from the graveyard to your hand if cast with no permanents in your graveyard.
• Mutated creatures are now counted as one creature with Settle the Wreckage, as they should be (702.139c of the Comprehensive Rules).
• A mutated Cavalier of Thorns should no longer be able to target “itself” if you chose to exile it when it dies.

You can read the full patch notes on the MTG Arena forums.