Board Thread:Question and Answer/@comment-71.57.16.138-20150204225155/@comment-25151790-20150205001603

When you defeat an archwitch and claim the reward, you will have a small chance of getting an SR. About half of the time it will be the archwitch itself, and sometimes you will get a different SR. You cannot get limited time SRs, such as past archwitches, limited enemies and summon exclusive cards this way, but there quite a few cards available.

This symbol on a card's page means that it is available from archwitches: