Do lost souls reactivate every turn or just when they enter play (and then remain active?). Couldn't find anything in the REG and I don't see any souls that point to one way or another.
At any rate I'd say "When you draw this soul [or maybe when this soul enters play], holder may search any deck for a lost soul and put it in owner's land of bondage.", just so it matches the wording of other souls and doesn't scare me with change.
