If you control no face-up monsters, or all face-up monsters you control are LIGHT Fiend monsters: Special Summon 1 "Fiendsmith Token" (Fiend/LIGHT/Level 1/ATK 0/DEF 0), also you cannot declare attacks for the rest of this turn, except with Fiend monsters.
If a face-up "Fiendsmith" monster(s) you control is destroyed by an opponent's card effect while this card is in your GY: You can Set this card.
You can only use each effect of "Fiendsmith's Sanct" once per turn.