Ok, at a keyboard, finally.
I think there are two definitions of "winning" in this thread and the other, and the differences between them are causing miscommunication.
It's been said that whichever mage is furthest ahead in the damage race is "closest to winning" and should therefore win a tiebreaker. But if you define "closest to winning" like that, it no longer means "most likely to win". You create a whole class of possible games where Alice is most likely to win -- but Bob is "closest to winning". This is a problem.
Imagine a game where Alice has 20 life left, and Bob has 25. We might say that Bob is closest to winning. But if Alice has 3 Dire Wolves and Bob's got nothing, then Alice is much more likely to win. Alice is
winning. And any measure that says that Bob is closest is measuring the wrong type of distance.
This creates perverse incentives for the players. Bob may realize that if he continues to press the attack he's doomed, but can try to flee and avoid conflict and somehow salvage a tiebreaker win from a game he could otherwise only lose.
Or remember that article Piousflea wrote about how important it is to get your opponent down to a low level of life? His reasoning was that once they're at risk of dying next turn they have to change their strategy and must make short term plays instead of long term plans. This is because only the last life point matters, and until your opponent is in a position to take that last life point, you don't actually have to make sacrifices to save your hide.
Well, if we award the game to the player with the most life, we're suddenly making all the life points matter, not just the final one. That 1 damage you took on round 3 is now very important, not just because it made death somewhat more likely, but because it's a victory point of equal value to all other victory points.
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So, how does the current tiebreaker system affect the current meta?
It rewards mages with access to frequent and large attack spells. 4 consecutive Hurl Boulders might do maybe 20 damage to an opponent with some armor, but they won't kill him or her. And in a long game, the player who invests in some armor and a belt of Regrowth and some creatures will win against an All-Boulder-All-The-Time strategy. But for most of the game the creature mage will have less health than the Boulder mage, even if the creature mage almost immediately has a much higher chance of winning.
This effect makes Wizards Tower even better, because Wizard's Tower's weakness is that you have to spend mana on Attack spells when you'd usually be better off investing it in a creature or conjuration. But now, since whomever is at lower life dies when time is called, short term tactical play beats long term strategic.
Or consider Sardonyx. He's big and mean and can probably help you win the game, but he's costs you 2 life a turn. Which, if you've got 20 life remaining isn't a big deal. But now, suddenly when time is called, you don't have 20 life remaining, you have the difference between your life and your opponent's life. That 2 life loss a turn goes from being 10% of your life to 50% of your life in a real hurry, and now Sardonyx is a bad investment.
Frankly, if the old Tiebreaker didn't help Wizard so much, I think I'd be more ok with it. Yes, it looks like it helps Warlock and Beastmaster, but it's Wizard who's best at crunch time nova damage because of an elemental training and Wizard's Tower. I really don't think we need to be making Wizard even stronger.