Teller of Tales

In Commander, Teller of Tales earns a slot specifically in high-volume spellslinger decks — the tap ability is effectively free if you're already casting three or more instants and sorceries per turn cycle, and a 3/3 flier has enough presence to matter in the air. Outside Commander, the card is legal in Legacy, Vintage, Modern, and Pauper, but it sees essentially no play in any of them — five mana for a tap-on-cast effect is too slow in formats where the game is often decided by turn four. Pauper is the one format worth a second glance, since evasive bodies at common are useful, but even there the cost is prohibitive against aggressive red decks. Stick to Commander, and only in decks casting enough spells to trigger it multiple times per round.