Why a player summon can be refused or consume its reagent before acceptance.
The reviewed CallPc handler refuses dead, rooted, fighting, shop-mode, observer and Olympiad targets, with further festival/event and prohibited-zone checks. The summoner instance must allow summoning; Seven Signs dungeon eligibility is checked separately.
The confirmation lasts 30 seconds. When the effect specifies a target-side item cost, this implementation checks and consumes that item before sending the invitation. Reagent quantities come from the exact skill parameters; do not assume every summon uses the same item or price.