Hearthpwn

Seems like it should - plenty cards have a negative interaction with coin (rogue classic prep - coin - concede). 

Yet more hidden interactions from Blizz....

There's no such thing as summoning a minion with 0 hp.

I‘m pretty certain Spirit of the Tiger summons a 0/0 that dies immediately if you play a 0 cost spell.  So does the spellburst effect of Ceremonial Maul if I remember correctly.  So I was also wondering why a 0 cost spell doesn’t use a charge and summon a 0/0.  If the keyboard isn’t intended to trigger off a 0 cost spell it should say so in the text.

As a side note, Reflecto Engineer can swap minions in your hand to have 0 health, and they die immediately after being played.

Quote from Thonson >>

I‘m pretty certain Spirit of the Tiger summons a 0/0 that dies immediately if you play a 0 cost spell.  So does the spellburst effect of Ceremonial Maul if I remember correctly.  So I was also wondering why a 0 cost spell doesn’t use a charge and summon a 0/0.  If the keyboard isn’t intended to trigger off a 0 cost spell it should say so in the text.

As a side note, Reflecto Engineer can swap minions in your hand to have 0 health, and they die immediately after being played.

 Spirit of the Tiger does not summon a 0/0 if the spell costed 0. However, Ceremonial Maul can summon a 0/0. Add in other cards with similar effects like Raj Naz'jan, Arcane Artificer, or Deepwater Evoker not triggering their effects for 0-cost spells, there is precedent for 0-cost spells being ignored for these kinds of effects. Maul's exception is likely due to the fact it's Spellburst, which does not discriminate based upon spell cost.

Source: Just tested it in-game.

Quote from CallmeChilli >>

There's no such thing as summoning a minion with 0 hp.

 I'm certain this is wrong as minions with swapped stats can end up with 0 health and die immediately (or are you making a distinction between  played and summoned?).  Given that corpses now matter, perhaps these cards should summon a 0/0 mnion. 

 Quote from DatMageDoe >>

Quote from Thonson >>

I‘m pretty certain Spirit of the Tiger summons a 0/0 that dies immediately if you play a 0 cost spell.  So does the spellburst effect of Ceremonial Maul if I remember correctly.  So I was also wondering why a 0 cost spell doesn’t use a charge and summon a 0/0.  If the keyboard isn’t intended to trigger off a 0 cost spell it should say so in the text.

As a side note, Reflecto Engineer can swap minions in your hand to have 0 health, and they die immediately after being played.

 Spirit of the Tiger does not summon a 0/0 if the spell costed 0. However, Ceremonial Maul can summon a 0/0. Add in other cards with similar effects like Raj Naz'jan, Arcane Artificer, or Deepwater Evoker not triggering their effects for 0-cost spells, there is precedent for 0-cost spells being ignored for these kinds of effects. Maul's exception is likely due to the fact it's Spellburst, which does not discriminate based upon spell cost.

Source: Just tested it in-game.

The Spirit of the tiger is an interesting analogy.  I didn't realise it doesn't work like that because no one ever really played it.  The difference between Cosmic Keyboard and the other cards listed though, is that they don't use up a "charge" when triggered.  All of them could concievably be triggering without animation behind the scenes (although given how this game works that's unlikely). Also, how do you know Deepwater Evoker isn't triggering (unless you're saying it wont draw a zero mana card, which seems like a bug)?  Why should spellburst not distinguish between a zero mana spell and one that costs mana, but Cosmic Keyboard does?  Also - Medivh, the Guardian. The weapon does trigger on zero mana spells as does Spirit of the Frog (which is logical but inconsistent with other the effects you've just stated). 

It really bugs me that there's such inconsistecy in the wordings and effects between cards.  I've stated it in another thread, but there should be NO secret rules.  None.   These cards could be worded "when you spend mana on a spell do X equal to the cost".  Easy fix, zero mana spells work as expected.

Instead we get a "nudge-nudge, wink-wink, secret handshake" ruleset that you can't possibly know what's going to happen in certain scenarios.  It's often challenging to work out why you got a certain outcome when a series of effects trigger (which is fine) but at least you can (usually) work it out.   You can never work out hidden rules (and with the likes of secret "discover" rules you can never know if you were just unlucky).