Did the Eelfinn know Mat would be returning when they gave him the ashandarei and told him “Wise to take leavetaking, etc…”?
They don’t have perfect knowledge of the future (think Dreamers) but they knew it was a possibility. Also, they gave him the ashandarei in fulfillment of his request for leavetaking, but were hoping he would not realize that, and be trapped in their domain.
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