@AseahawkfanCan I use Overchannel to cast 3rd level spell [I]fireball[/I] using a 7th level slot? Seems to read that way.
It won't work, since that fireball is 7th level. The level of a spell matches the level of the slot used to cast it (PH, 201).

— Jeremy Crawford (@JeremyECrawford) May 14, 2015

@JeremyECrawford It looks like monsters use their proficiency to calculate saves/skills. But there are some exceptions like Lich's Arcana

— Mark Lenser (@MLenser) April 5, 2015

A monster's save or skill bonus includes its proficiency bonus (MM, p. 8) and maybe Expertise or an ad hoc modifier. https://t.co/fRockHqbtx

— Jeremy Crawford (@JeremyECrawford) May 14, 2015

@JeremyECrawford The article "The ability check" 30/4/15 see picture, this isn't stated in the spells description. pic.twitter.com/B6o3IANsSL

— Kevin G (@a1104477) May 13, 2015

@a1104477 The highlighted portion refers to the rule for all spells that use a bonus action. See page 202 in the Player's Handbook.

— Jeremy Crawford (@JeremyECrawford) May 13, 2015

@ChrisPerkinsDnD ChisbestDM, I have one power player in my game, how do I restrict him but also deliver him spotlight? Sorry my English.

— Bob_Zombi (@Voodoo_Jedi) May 9, 2015

You know your players better than I do. I would ask the other players what they would do, and get them to help. https://t.co/ieeymJcOe6

— Christopher Perkins (@ChrisPerkinsDnD) May 9, 2015

@happylittlelarkAs a DM do you have any guidelines as to how often I should be awarding Inspiration? Try awarding inspiration at least once per session. I enjoy letting the players award it. Check out the DMG (p. 240).

— Jeremy Crawford (@JeremyECrawford) May 7, 2015