Weekly Team/Character Building Megathread (Jan. 4th, 2022) (feat. Shenhe & Xiao)

A megathread dedicated to team/character building Q&A.

Do not post questions irrelevant to team/character building here. They should belong to the Daily General Question Megathread.

If you have a comprehensive theory (rather than a question) about how to build a character or a team, you are encouraged to make a dedicated discussion thread outside this megathread, as it can help general players.

This week's team/character building megathread will feature Shenhe & Xiao. If your question involves them, you are strongly encouraged to start your question with a "[Shenhe]" or "[Xiao]" tag, like this:

[Shenhe]
insert your question

If your question does not involve them, the following template is recommended:

Character(s): insert character(s)
insert your question