If this card is Normal or Special Summoned: Place 1 Spell Counter on it. You can remove 1 Spell Counter from this card and discard 1 Spellcaster monster; Set 1 Continuous Spell directly from your Deck, but for the rest of this turn you cannot activate it, or activate cards, or the effects of cards, with its name. You can only use each effect of "Rogue of Endymion" once per turn.
If your plan is to summon him on opponent's turn so you can activate the continuous spell on your next turn, let me inform you: the "remove spell counter to set a continuous spell" effect can only activate on your own turn.
So you're just putting 1 useless monster on the field until your next turn, where you'll be putting 1 useless continuous spell on the field.
This card is crap
Setting a Continuous Spell and not even allowed to activate it.....not only the opponent knew what card it was (so no bluffing), but it's also useless until the next turn, and that's assuming the card survives until then.