For the first time since a long, long time all the three weekly winners are EDH related. Battlebond is having a big effect on card prices!
Even though you only need one copy of your commander for your EDH deck, a sudden interest in a commander that is not printed outside a set like Commander 2015 can seriously drive up the price. The total print run of these sets is lower and they are opened mainly by EDH players, making those sets kind of a niche compared to 'regular' sets like Dominaria. Simple supply and demand that drives up te price as more people are interested in running Ezuri, Claw of Progress.
Ezuri, Claw of Progress sees play in different types of EDH decks, ranging from Elf Tribal, to infect, tokens and even as the odd man out in merfolk decks. But since Battlebond, one particular EDH strategy around Ezuri, Claw of Progress has popped up: +1/+1 counters. The reason? The printing of these partners: Toothy, Imaginary Friend and Pir, Imaginative Rascal. Those two give EDH +1/+1 counter decks increased synergy and this attracts new players to the archetype.
Dominaria as enough to bring to the table for EDH as well. Jodah, Archmage Eternal for example. This commander itself costs only $0.49 but it is gaining traction in EDH since its printing. Together with Najeela, the Blade-Blossom it fits a 5-color strategy that trades access to all legal cards in any color for you having to have 5 types of mana to really get somewhere.
Bringer of the Black Dawn fits nicely in the 5-color strategy, especially with Jodah, Archmage Eternal (it only sees very minor play in Najeela decks). With Bringer of the Black Dawn, you can tutor for any card for just 2 life. Every turn. This is powerful in EDH because decks are 100 cards and you can play only 1 copy of each card. Having the ability to find the specific card you need to get ahead is great.
As always with cards like Bringer of the Black Dawn, it doesn't see play in just Jodah, Archmage Eternal. Check out EDHREC for the complete list of commanders associated with the card.
This is where Najeela, the Blade-Blossom really comes into the spotlight. The printing of that commander pushes the Warrior archetype to the forefront and gets EDH players looking for any and all warriors that might fit into a token baking, extra attack phase beatdown strategy.
Stonehoof Chieftain fits the bill since its not only a warrior, it has trample, indestructible and gives all your other creatures indestructible as well. And that's extremely helpful when you get extra attack phases since your army is completely indestructible and tramples right over opposing forces and if your opponent survives you get such an amount of life that you'll be far ahead.
This synergy renewed the interest in Stonehoof Chieftain and pushed it price over $15 this week. After a $17 spike the price is falling back a bit over the last few days.