If a permanent’s ability instructs a player to “monstrosity X,” other abilities of that permanent may also refer to X. The value of X in those abilities is equal to the value of X as that permanent became monstrous.
September 25, 2020 · Zendikar Rising
If an effect instructs a player to meld objects that can’t be melded, they stay in their current zone.
July 3, 2020 · Core Set 2021
If an effect instructs a player to meld cards that can’t be melded, they stay in their current zone.
August 23, 2019 · Commander 2019
Once a player has goaded a creature, the same player goading it again has no effect. It doesn’t create additional combat requirements.
April 27, 2018 · Dominaria
rule 701.37c not present in this release
April 28, 2017 · Amonkhet
An object that isn’t on the battlefield can’t be exerted.