­Unholy Strength + Greater Improvement

One of the real old iconics, that told us "Black gets power, white gets toughness"

And... upgrade an artifact into another one, and then proliferate them... which is, um, either put an extra counter onto all artifacts, or add extra artifact tokens. I choose to assume the former, though the latter has legs.

Anyway. The names are wonderfully similar in feeling - flavour is a demon reaching down and.. improving things.

So - how do we give artifacts an unholy upgrade?

Well, one way would be to change their activation costs into life costs. Lots of extra uses, at a cost of pain, ifs a very black thing. And if the cost is high, potentially usable offensively.

That works, I guess.

Was going to make this variable life cost, so it was more obviously tunable for either you or your opponent; but that probably ends up a bit too good - so fixing it in the middle of my range.

A bit good on the Tower of Fortunes cycle, which all cost to cast and to activate. Especially amusing on Tower of Eons :)

Is this intended to replace sacrifice costs too? I fear it might, which would make even the humble Pyrite Spellbomb or Aether Spellbomb a pretty terrifying object (and once again goes infinite with Sunbeam Spellbomb... in fact, it goes infinite then draws your deck).

Hmm, I was worried about life-gain ones, which is why I set it at 3. I guess I could say that just "Mana and tap costs" are replaced.

Well, I can check "You're right, activating sunbeam spellbomb for free is more broken than activating mindslaver for free" off the list of sentences I never thought I'd type :)

Very nice design though, I'm not sure what the best adjustment is.