There's been Vedalken Orrery and assorted variants, the most recent of which are Hypersonic Dragon and Alchemist's Refuge. But Rachael pointed out that there's never been an equivalent for activated abilities (apart from equip abilities as on Leonin Shikari). Many activated abilities, especially keyword abilities such as scavenge (Slitherhead), transmute (Drift of Phantasms), unearth (Fatestitcher) and level up (Kabira Vindicator), have sorcery-speed restrictions that are for sensible reasons, but nonetheless seem like the game could cope fine with them if they were instant-speed.

(This is usually where SadisticMystic steps in to point out how crazy broken this is with some obscure card from Magic's history :) But it seems a conversation that'd be fun to have, at least!)

Humm. I would guess equip would be the most obvious point of attack; but that's already been done I think.

Allowing level-up to be instant speed is darn nice; but hardly game breakingly so. Yeah, I think I like this.

I'm wondering how this works with loyalty abilities. Is it effective at all, and if so then does it create a separate permission that bypasses the normal loyalty ability permission (allowing unlimited activation à la the old days of Experiment Kraj)?

Hmm. I don't know how it does work. If I were in charge of making the rules work with this card, I'd want to put loyalty abilities in the same category as playing a land: something you can't do outside your turn ever at all, and only once (per planeswalker) on your turn; but beyond that, normally with sorcery-speed restriction, but other cards/effects can bypass that if they want. So this would let you use Ajani Vengeant as an on-board combat trick in your turn, but not in other players' turns.

I'm pretty sure it doesn't actually work like that at the moment, but ideally it should. At the moment it does indeed probably either not work at all, or break horribly with planeswalkers and need a fix to one or the other.

Brutal with creatures that make players discard cards, but only at sorcery speed. You could certainly maneuver around it, but some games would be set and match as soon as the opponent's hand had zero cards, discarding player had superior board position, and the combo came down.

True. But this card was somewhat deliberately double-coloured-mana and not-black to make that somewhat harder to do, and they can also still play instant-speed removal spells in the draw step such as on this 2/2 creature.

Played at the Bring Your Own draft, this got very confusing. The second ability was meant to only override timing rules on abilities activated from hand (transmute etc) or graveyard (unearth etc), but people thought it meant you could activate Prodigal Pyromancer from your hand or graveyard, for example.