Stumbled upon an old question regarding Valakut and Dryad of Ilysian Grove, Link is below: Does Valakut do damage if Dryad of the Ilysian Grove is in play, but dies before the trigger resolves?
I am not quite following the ruling (Not a judge, just a lowly L0). In this case the effect is checked as it is being placed on the stack and also as it resolves.
In ruling 613.5 it states - The application of continuous effects as described by the layer system is continually and automatically performed by the game. All resulting changes to an object’s characteristics are instantaneous.
I would have thought that because the plains stops being a mountain due to dryad being destroyed, Valakut's trigger would not resolve. I understand the ruling with the mountain leaving the battlefield etc, but not quite this. I also understand another thread where Dryad loses all abilities but because losing ability is applied at layer 6 and type changing ability is applied at layer 4, even though dryad loses all abilities the lands are still every type. Thread as below: Why does Dryad of the Ilysian Grove grant all basic land types even if it loses all abilities?
Do explain why if Dryad dies as lands enter, when Valakut trigger resolves the it still does damage?