If Outpost Siege (choosing Dragons) leaves the battlefield at the same time as any of your creatures (e.g., from Perilous Vault), the game looks back to see that it should trigger, and you'll get the 1 damage per creature you were hoping for!
Category: Triggered Abilities
An interesting situation with Kira, Mutavault, and Tec Edge.
Kira grants an ability to your creatures that triggers when the creature becomes targeted. But if Mutavault is targeted before it actually becomes a creature, it will be too late for the ability to do anything to a spell or ability already on the stack.
Flamerush Rider copying Mardu Hearpiercer
Flamerush Rider trigger when it attacks, which means any token copy of a creature with a Raid enters-the-battlefield ability will trigger accordingly when the token is created.
Yasova Dragonclaw pays for the trigger only on resolution
Yasova Dragonclaw's ability is a little tricky. You can't make the controller pay mana for it while not giving up control of the targeted creature. If you have a response, you have to do so after a target is chosen, but before any mana is paid.
Collateral Damage sacrificing Monastery Mentor
Collateral Damage requires the sacrifice as you pay the costs, which is before the game considers it "cast" for trigger purposes. So if you sacrifice Monastery Mentor to pay for it, it won't be around long enough to trigger from the casting, and you won't get a token.
Manifest and Gift of Immortality
Gift of Immortality can return any permanent card that it was attached to if the card was a face-down manifest creature when it died. It can't return an instant or sorcery. Details inside!
Manifest and Athreos
Athreos triggers when any of its controller's creatures die, and no matter what they look like in the graveyard, they can still be returned unless 3 life is paid.
Containment Priest vs. Flickerwisp
A creature that "flickers" under the purveyance of Containment Priest is not going to be able to come back to the battlefield.
Casting a god doesn’t trigger prowess (but a bestowed card will).
A god spell will always be a creature, and thus can't trigger prowess. But a bestow card cast as an aura is indeed a noncreature spell, and can trigger prowess.