After the boss finishes its turn by attacking, the damage the players built up against it during their turn finally "hits" the raid boss
This gives your opponent a hint at what might be about to come their way, and even when you put a creature into play, they usually cant be used to do damage until the next turn, unless the card is an instant, a category of card thats yet another exception to the rules
It's still not a bad card to have, though
New Subtypes Incubator Siege The Abyss Amonkhet Antausia Arcavios Capenna Cridhe Echoir Eldraine Fiora Gargantikar Bobakhan Ikoria Ixalan Kaladesh Kylem Shenmeng Tarkir Theros Zhalfir New Glossary Entries Backup Defense Incubate Incubator token Protect Protector Siege Updated Glossary Entries Battle Chaos ability Chaos symbol March of the Machine Oracle Changes There are a few cards receiving errata to their Oracle text with the release of this set
Here is one example of how they are valued
Birthing Pod reminds me of the build-around-me enchantments that the color used to get like Aluren, Earthcraft, and Survival of the Fittest