@desolutionist said in Claim the Firstborn:

The fact it doesnt steal creatures greater than three is a limitation and that probably makes it more limited unplayable than the hyper efficient constructed formats that are choke full of amazing 2 and 3 cmc creatures.

This will see play in many other constructed formats:

In standard, mono red has been consistently good and most decks play on something of a curve so you will have targets.

In modern - Burn will play this in the board at least in some number as it lets them punch through a few tougher road blocks they normally have issues with, namely Goyf and Ooze but there are a number of others. Being one mana cost is a huge deal there because Boros charms Doublestrike mode suddenly becomes more relevant than the deal 4. Mono red prowess will also run this for similar reasons.

In legacy - Basically burn as in modern but also I suspect some sort of aristocrats style deck or jund. Will be used more strategically there than in modern I suspect.