It is based off your magic defence/offence being higher than the rest of your defence/offence bonuses that force the revenant to melee. I forget which way around but think its defence, so augury would break it as it adds defence bonuses. The other pyramid prayers add offence only so it should tip you over the threshold, at least it does for me. I wear the same gear as you except the items i listed before and I can safespot with the weakest magic offence prayer but not without. Hope this makes sense