Perfect for sacrifice decks, especially when combining Experimental Confectioner with cards that make expendable tokens
(I know I'm harping on Diablo a lot in this set review, but he is the biggest Evasive threat in the format right now, so ways to deal with him are going to be paramount.) Outside of her usage as a Diablo counter, she is just a decent body that can Rush down lots of cheaper characters, even when they are readied
Legality depends on the tournament format -- Liliana, Waker of the Dead can be legal in some formats and banned or restricted in others
However, if there are not creatures on the battlefield, then Tamiyo doesnt do a whole lot
If you'd rather not play and just want to hang out and trade, or play even less formal One Piece games, that's okay