Quick question: I have no graveyard and only Timetwister in hand. I play said Timetwister. Do I still shuffle? Please back up with Comprehensive Rules.
Each player always has a graveyard even if no cards are in it (C.R. 400.1; see also C.R. 404.1, which says: "Each player's graveyard starts out empty"). When Timetwister resolves:
If you have no cards in your hand and no cards in your graveyard, you simply shuffle your library (C.R. 701.20d).
If you have no cards in your hand, but one or more cards in your graveyard, or vice versa, you shuffle all cards in your hand or graveyard, as the case may be, into your library (C.R. 701.20d, 400.11).
EDIT (Mar. 17): Added rule citation.
EDIT (Dec. 23, 2020): One rule was renumbered in the meantime.
Thanks.
EDIT (Mar. 17): Added rule citation.
EDIT (Dec. 23, 2020): One rule was renumbered in the meantime.