Tenshi is one of the most popular characters in Danmaku!! Since Tenshi originated in one of the Touhou fighting games, she is all about challenging people. In fanon, she is also often depicted as a masochist, so we gave her an ability where she wants to get hurt. She wants it bad.
Her spell card, Sword of Swagger, allows her to draw two cards and mimic the Challenge card. If Tenshi loses the challenge she gains yet another 2 cards thanks to her ability.
Tenshi is fun because she rewards players for playing recklessly. She can overextend herself though - if she runs out of defense and can't draw more, she may get more punishment than she asked for.