Courtesy of Wizards of the Coast’s First Look: Web Exclusive, check out the Boros companion from Ikoria: Lair of Behemoths – Zirda, the Dawnwaker!
In the ninth previewed companion creature, we have a three-mana 3/3 Elemental Fox that looks to facilitate some busted combos.
Companion – Each permanent card in your starting deck has an activated ability. (If this card is your chosen companion, you may cast it once from outside the game.)
An interesting and difficult restriction to meet, but one that is incredibly powerful when you look at the next ability on Zirda.
Abilities you activate that aren’t mana abilities cost 2 less to activate. This effect can’t reduce the mana in the cost to less than one mana.
In a fair world, this ability incentivizes you to play a fun deck filled with abilities. In the Magic world, it means play Grim Monolith or Basalt Monolith and create infinite colorless mana. Plus, since the deck-building restriction only applies to permanents, you can put whatever massive X spell in your deck to win whichever way you like.
In Standard, this reduces the cost of the Castles from Throne of Eldraine and the Gods from Theros Beyond Death, not to mention the many artifacts available in the format.
If all of that wasn’t enough, there’s another ability tacked on that fits with the Boros flavor of the card.
1, T: Target creature card can’t block this turn.
So, if Zirda fits into a creature deck or finds itself needing to push lethal, it can also clear the way for attackers.