If you have "Mystical Space Typhoon" in your GY, or your opponent controls no Spells/Traps, you can Special Summon this card (from your hand). You can only Special Summon "Radiant Typhoon Swen" once per turn this way. If this card is Normal or Special Summoned: You can add 1 "Radiant Typhoon" Spell/Trap or 1 "Mystical Space Typhoon" from your Deck to your hand. You can only use this effect of "Radiant Typhoon Swen" once per turn.