Good policy as a rule. Let's see... Sigyn can control plants or heal people. Most of them are healers though, and there aren't many who I know that are powerful at controlling plants. Jades one of the only strong ones. The other healers are in Heimdall, but they have to take the wounds on themselves to do it, so there's serious limits. They're either sharing their energy with other people, or they're taking their wounds.