Great idea, but what would happen if you get somethng like Sacrificial Pact and Frostbolt? I think you should go with the 2nd version, but I think you should come up with a rule for if one target is not eligible for that spell.
Exactly that example has come up already. Limitations still apply, so you could only target a Demon with that card. It would deal 3 damage and sacrifice it to heal you. If you choose Power Overwhelming and Freezing Potion, you couldn't play the card, since you can't target anything. Gotta choose wisely.
@Your cards. I think Mana Leech is the most interesting. The artwork isn't really fitting tho. I think it would work as 3/3 for 3, too. The effect is rarely happening and has little to no effect late game. 2 Mana 2/3 might work even.
I always want to damage my own face like a pro. And make self damaging warlock more viable
I like neither of them tbh. The first is very, very clunky to play and the second makes thematically no sense. It's also very clunky to play and more of a gimmick than anything else. You could do something like "At the start of your next turn, restore health to your hero equal to double the amount of damage received this turn." or something. The whole aspect of "self damage" also only truly fits warlock, so I don't think this will work with any of the other classes. Tho, in Rogue you receive damage during your turn when you attack into something. Maybe a minion with a deathrattle that grows whenever you receive damage during your turn? e.g. "Whenever your hero takes damage during your turn collect 2 Life. Deathrattle: Restore health to your hero equal to the life collected." I dunno.
You discover a mage spell and then a warlock spell. If you are too greedy, you might end up with a 11+ mana cost card or cards that don't mesh well together, e.g. Mirror Images + Hellfire. I'm unsure about the balance. It might be too weak. I also have a version in mind with "It costs (2) less." to give a bit of leeway and actually be able to cast more spell combos. Alternatively, I could limit the effect to 5 or less mana costing spells to ensure castability.
Anything game breaking in mind? Anything unclear? Which version do you like more?
I really like the core concept of this but MAN is this effect hard to get in line.
I'm currently leaning towards #2 because i don't really like the possibility to create unplayable spells. I'm all for cards that have players focus on what they're doing but the there's just so much room for little errors (due to little errors in reasoning, tiny lacks in concentration, misclicking, etc.) that leave you with a blank 4 mana 4/3 and a useless card to clog up your hand. Tl;dr: I prefer a version that somehow guarantees you a playable card - playable regarding the mana cost that is.
I'm not sure #2 is the best solution though. It limits your options to a lot of little utility and/or value packages - which can be good. But i think it locks you away from the big tide-turning plays and those are probably the ones you will be shooting for with a card like this. And if it's possible to be left with something horrible like Mirror Image + Sacrificial Pact, i think you also need to cover the other end of the scale. Also, most of the spells at 6 or more mana are the big board clear effects of both classes which - if combined - would often be quite redundant.
I'm thinking about adding something like "It can't cost more than (10)." into the equasion - meaning that anything costing more will be discounted - but i kinda doubt that would fly on anything other than a legendary (might be problematic even then). On the other hand getting exactly something like Pyroblast + Twisting Nether - albeit really nasty, if actually pulled off - is pretty unlikely since getting a specific spell from one class is pretty low with 30ish cards in each pool.
Discounting is also a neat way to allow for some more combination space but i'm not sure how that would still fit within 4 lines of text without looking really weird. So as long as you don't necessarily want to make this into a legendary, the best version i came up with is to go with #1 and apply a restriction to the card's mechanic: You could limit the second spell-discovery only to cards that still fit into the "10-mana-window" - so if you pick Flamestrike as your first spell, the second discovery will be limited to cards that cost 3 or less mana.
This would need some additional explanation for the card though, since you can't specify such things within the card text. That is kind of a flaw because people probably don't like to read - i know, what morons! - but i think your effect catches the eye enough to encourage people to do so anyway.
So another Tl;dr: I'd like #1 more, if combined with a mechanic-restriction that dynamically limits your options to a maximum total of 10 mana cost. Otherwise i'd go for #2 and maybe add some sort of discounting the total mana cost, if you can somehow pull that off.
Finally i hope this wall of text could be of some help and wasn't just time-consuming busywork :)
I'm not really sure about why this costs (4). Sure, having extra Warleaders in your deck is great, but you're losing some board presence and paying more for it, which seems like just a tad bit too much.
I dunno, if you were proposing letting those two decks essentially have 4 copies of arguably their most powerful card, I would at least hope it was a worse copy.
You need to have the board before hand, and if you've already a big field of murlocs, you were already in a winning position. If you aren't in a winning position, it's just a card that'd sit dead in hand forever.
I think this might even be balanced at 2 mana. Warleader costs 3 after all plus you need to already have board presence - which presumably costs mana too. Even if you combine this with Murloc Tinyfin, it is effectively a discount for (1) but spread across two cards - seems okay to me.
I also doubt that murloc decks actually play Tinyfin. But then again - i'm not really an expert on that... :D
After some more work on the name-department my favourite is still one of Toxibrah's suggestions:
As for alternate ideas:
Comrade in Arms
Thanks for the detailed feedback. I rarely see someone put so much effort into it. Sadly, I have submitted the card an hour ago or so. x) Still, I really appreciate the feedback. I went with the 2nd version, which limits everything to 5. Most people thought that it would be better, and it obviously is a lot more consistent, even if it's a bit less fun because you can get less (powerful) combinations. Like you said, making it not cost more than 10 would result in some broken plays, which is not always fun. Felfire Potion + Pyro is 15 damage. Not all that fun.
As for your card: I like Brother in Arms as name the most. It's catchy and a good depiction of the spirit of what the card is about. The effect is creative and feels apt for the classes chosen. Balance-wise it's actually very elegantly solved and after some thinking, I'm really impressed. It's strong but has counterplay options - my favorite kind of card. My only suggestion on how to improve it, would be to slightly pull the card art higher, so you have less sky in the picture, but that's really about it. Otherwise, change the tag to Un'Guro - some people put value into that.