@JeremyECrawford Please answer! I'm tired of spamming this. If I have a Pegasus from Greater Find Steed then true polymorph it into a Silver Dragon Wyrmling, the wyrmling still has a lifelong bond and has a telepathic link, correct?
— s (@sethmhilliard) November 25, 2017
One spell doesn’t end another spell’s effects unless (a) one of them says it does or (b) a general rule says it does. For example, no rule says polymorphing your supernatural steed has any effect on your bond with it. #DnD https://t.co/70yFEyUDGi
— Jeremy Crawford (@JeremyECrawford) November 26, 2017
According to this tweet https://twitter.com/JeremyECrawford/status/931621590730653696 … it would seem that the effects from Find Greater Steed are suppressed while the creature is not one of the possible forms. It’s still your steed. Polymorphing it doesn’t change its magical relationship to you.
— Jeremy Crawford (@JeremyECrawford) November 27, 2017
If Polymorph suppresses charm, and replaces all game statistics, the statistics of the creature from a Greater Find Steed spell (including int, ability to speak, telepathic communication, etc.) should be suppressed. The bond between the paladin and the steed isn't one of the steed's game statistics.
— Jeremy Crawford (@JeremyECrawford) November 30, 2017
Frankly, I was a bit surprised when you ruled that Polymorph would suppress the effect of Charm Person, since I didn’t think that a condition was a part of creature statistics and since Charm Person does not have any continuous check for creature type. To be clear, I haven't ruled that polymorph suppresses charm person. I said there's no rule and gave a rule of thumb (a house rule) you might want to use. There is no official ruling on this point.
— Jeremy Crawford (@JeremyECrawford) November 30, 2017