[work in progress?]Drain Life and cost reduction

[Korath]

Describe the Bug:
I have two Jet Medallion and four Swamp on the battlefield. I cast a Drain Life and tap all available mana. X is 3. fixed

Which card did behave improperly ?
Maybe Drain Life. More likely the cost reducing engine.

Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
FRF.

What exactly should be the correct behavior/interaction ?
X should be 4. I can't find chapter and verse in the comprehensive rules, which is supremely irritating, but rulings from the two cards:
Jet Medallion: 10/4/2004 The generic X cost is still considered generic even if there is a requirement that a specific color be used for it. For example, "only black mana can be spent this way". This distinction is important for effects which reduce the generic portion of a spell's cost.
10/4/2004 The effect is cumulative.
Drain Life: 10/4/2004 Cost reducers can be used to reduce the X part of the mana cost.

So get from the swamps and reduce cost by from the two medallions, and the sorcery should cost with X=4.

Are any other cards possibly affected by this bug ?
Atalya, Samite Master, Consume Spirit, Crimson Hellkite, Crypt Rats are the other cards in Manalink with restrictions on what can be spent on . Jet Medallion doesn't apply to any of them except Consume Spirit, of course, but there's Training Grounds and Dragonspeaker Shaman and plenty of other cards that do.

[SytheLunat]

The calculation is correct in the program.

Since Drain Life can only use Black Mana as the X value, your jet medallion only has 1 generic mana in the spells cost to reduce.

Effectively to cast the spell for 4 damage you need 5 black sources

For drain life's purposes, think of X as a variable number of black mana symbols [(B)(B)(B)] (1) (B) for 3 damage or [(B)(B)(B)(B)] (1) (B) for 4 damage etc.

This also applies to your other examples, because they have mana restrictions "spend only [color] mana on X"

[Korath]

That's a common misconception, but it's false; see the rulings I linked. A cost reduction isn't a payment, so it isn't affected by restrictions on how you pay that cost. Relevant rules are 601.2b (X is chosen at proposal), 601.2f (total cost is modified by cost reductions), 601.2h (payment begins).

If I recall correctly, the way this worked changed shortly after Tempest was released specifically because of this issue; previously, Helm of Awakening had been ruled not to affect Drain Life's X cost.

[Gargaroz]

Fixed for the majority of cards via "generic_spell" and for Drain Life / Consume Spirit via their specific functions.
Activated abilities shouldn't be a problem, as both Training Grounds and Power Artifact have the clause that they coulnd't reduce the activation cost to less than 1.

[BAgate]

Atalya, Samite Master + Training Grounds no effect.

Drain Life / Consume Spirit + Jet Medallion - same bug. fixed
Plus, Drain Life and Consume Spirit don't do anything on resolution. fixed

[Gargaroz]

Drain Life fixed in 5a5f172
Consume Spirit fixed in 0b6ee81
Interaction between both and cost reduction for spells fixed in 4ad10ae. This was a global bug and will fix all the other bugs like the interaction with additional costs.
I'll work on the same bug for activated abilities too.

[Aswan jaguar]

Drain Life & Consume Spirit have been fixed.
Also they work correctly with cost reduction with Jet Medallion at least that I tested. They do deal correct amount of damage and gain life accordingly with 2 and 3 Jet Medallion in play. Only the X you see when you cast the spell is still wrong which if I remember correctly is hardcoded can't be fixed, right?

Edit: The other 2 I found that reduce cost of black spells, Stormscape Familiar and Thunderscape Familiar work also fine with Drain Life & Consume Spirit.