Since we don't have any blockers, this means that Sleeper Agent actually says we take three damage a turn (from being attacked) while our opponent takes two
Kokusho is the most famous of the five legendary Dragon Spirits, and its effect scales up well for multiplayer games, too, while the same can't always be said for its counterparts in other colors
If a creature dies, it is sent to your graveyard and you can only get him back onto the field with certain abilities
On your turn you are safe from opposing spells and many abilities too
Having a one-mana counter spell for creatures is almost unheard of, as most one-mana counter spells are against non-creature spells
While this is not quite the power level of Skullclamp it does have the added perks of doing stuff on its own and not needing extra mana investments to keep it operational