a) what dictionary do you use that doesn't include geas?
I should think most English dictionaries wouldn't - the word is Gaelic.
Yes, I'm aware. Technically it's Scots-Gaelic. My wife speaks Gaelic - thanks, great-grandma Carnahan! - still, it's a term that is used in English with increasing popularity. I just typed the word into Google, and it came up with the definition, along with it's etymology and usage over the past two centuries.
Actually, I'm done replying to this issue, as it's doing exactly what I was trying to avoid - distracting the conversation from the errata.
Back on topic though:
This is per one of the developers, Giabralter:Greater Spirit Powers
Guardian: Shielding (SR5 p. 326)
Guidance: Psychometry (p. 119)
Task: Compulsion (SR5 p. 395)