Stairs of Mail

During your Main Phase: You can activate this effect; discard 1 "Tindangle" card, and if you do, apply 1 of these effects. <br>• Change 1 face-down Defense Position monster you control to face-up Attack Position. <br>• Change 1 face-up Attack Position monster you control to face-down Defense Position. <br>This turn, you cannot discard another card with the same name for the effect of "Stairs of Mail" (even if this card leaves the field).