怂 is written with the 心 (xīn) radical on the bottom and the character for "Follow, From": 从 (Cóng), on the top. The original meaning of 怂 was to panic. Today, 怂 is used to describe a situation where one person is instigating another person to do something, often something negative.
To help remember 怂, borrow from the meaning of its top component character 从 (Cóng) "Follow, From" and how one person follows or complies with another person's advice or suggestion from a heart to heart conversation.