You can use decklists at Regular. You can even use them on prereleases if you want to (not recommended).
From the MTR 2.7:
"Players are required to register their decks and sideboards (if applicable) in Competitive and Professional REL
tournaments.
The Head Judge may require registration in Regular REL tournaments. “
And continuous deckbuilding is an option on Regular REL (and only on Regular REL), not a set feature.
From MTR 7.2:
”Players participating in Limited tournaments that do not use decklists may freely change the composition of their
decks between matches by exchanging cards from their deck for cards in their sideboard without being required to
return their deck to its original composition before their next match. The Head Judge or Tournament Organizer
must inform players if this option is not being used prior to the start of deckbuilding. This option is not available
at Competitive or Professional REL tournaments."
Edited Espen Skarsbø Olsen (Aug. 19, 2016 03:55:15 AM)