Five mana for a 5/4 trampler is a lot more attractive. With any sort of accelerant you can play it on turn four—and if your opponent doesn't have a removal spell, it's unlikely that he or she will have anything that can match it for another turn or two, allowing you to crack in for quite a bit of damage.
Four mana for a 5/4 trampler is pretty nutty. Imagine being on the play, opening with a turn-two mana accelerator and then casting a 5/4 trampler on turn three. A lot of the time your opponent will not have cast any spells by this point, so you'll have a 5/4, three lands, and an accelerator to your opponent's two lands.
Yes, that's right—there's a common 5/4 trampler for four mana that can be played in any deck. Heck, if you have a mana Myr—which is, admittedly, a little bit more difficult to pull off now that we open fewer packs of Scars of Mirrodin in our drafts and Sealed decks—you can cast Thundering Tanadon on turn three.
Just because a card costs green Phyrexian mana, that doesn't meant that you need to have green mana in your deck for you to play it. If you can cast the card using Phyrexian mana (and it's good), you can, and probably should, play it in any deck. Accordingly, regardless of what colors I end up playing, Thundering Tanadon is probably going to be in my deck. Yes, it's definitely nice to have the option to pay instead of and 4 life for my 5/4 trampler, but I'm not picky.
If I'm playing against an infect deck, then the life loss will be pretty much irrelevant. If I'm playing against a midrange creature deck, a dinosaur deck, or a grinding control deck (even if it has a ton of removal), then the life loss won't be that big of a deal, especially when you consider the immense amount of upside that you get from the fact that, well, your opponent won't always have the removal spell.
Pretty much the only times I'm going to feel bad about having Thundering Tanadon in my nongreen deck is if I'm playing an extremely slow control deck that needs to preserve every one of its life points, playing a deck that is exceptionally good in the late game, or facing an opponent who is playing something aggressive and has a number of good ways to kill artifacts.
What does this mean for you? As long as you don't think that you have a deck that can easily dominate the late game, you should probably put Thundering Tanadon in your starting 40, even if you don't have single green source in your deck.
"But Steve, if you're playing against an aggressive deck with a number of Shatter and or Arrest effects, then Thundering Tanadon will be quite the burden if you aren't playing any green sources. If you spend a whole turn only to lose 4 life and see your creature get Shattered, then you're probably going to lose."
Yes, it's true that it will be correct to sideboard out your Thundering Tanadon against most aggressive decks when you aren't playing green. But unless New Phyrexia changes things a lot more than I expect it will, then I don't think you'll have to worry about playing against all that many aggressive decks. And even if you are playing against an aggressive deck, there will be times when your opponent simply doesn't have an answer, or that fast of a draw, and you will be able to ride your Thundering Tanadon to victory (or at the very least a good two-for-one).
Play or Draw?
I know that there are going to be times when I will want Thundering Tanadon when I'm on the play but would choose to board it out for games where I'm on the draw. If the upside of playing an uncontested turn-three or -four 5/4 is overshadowed by the downside of getting your four-drop killed and losing 4 life when you're already backpedaling, then you might want to go for a safer option, particularly if you think that you are advantaged against your opponent if the game goes long.
If you think that your opponent's deck is significantly stronger than yours in the early game and the late game, then you might realize that you need to keep your Thundering Tanadon in because you need some high-powered cards in your deck that can potentially steal some games for you (even if they come at a somewhat steep cost).
The Limits of Phyrexian Mana
While I know that I am going to be happy to include a Thundering Tanadon in my nongreen decks, I'm sure that I'll hesitate a bit before I add a second one, and I will probably never main-deck a third one unless I have a number of mana accelerators.
It isn't that big of a deal to lose a few life to power out a card (or two) a couple of turns before you should reasonably able to do so, but if you fill your deck up with off-colored Phyrexian mana cards, then you are going to be particularly vulnerable to aggressive strategies – and even if your opponent isn't playing anything all that fast, you will find yourself in more than your fair share of situations where you've been slugging around for a dozen turns or so, start falling low on life and, just when you really need to pull away, you'll start drawing Phyrexian mana spells that you can't comfortably pay the life for, but you need to cast anyway.
How Much Life?
If you're playing Thundering Tanadon in your green deck then you will no doubt be presented with quite a few interesting decisions when you must choose between paying a chunk of life to cast your Thundering Tanadon early or waiting until you can pay the full six mana.
If you can play comparable cards at four and five mana, then you will often be better off waiting, especially if your opponent is putting some decent pressure on you. If you can cast artifacts that can act as lightning rods for your opponent's removal, then you will have a further incentive to wait to cast your Thundering Tanadon.
However, you should be careful not to play your Thundering Tanadons too conservatively. If you always wait until you have five or six mana to play out your Thundering Tanadons in your green decks, then you are going to miss out on some opportunities to seriously punish players who keep hands that are light on early plays.
I know that if I'm on the play and my opponent didn't just open on something like a Porcelain Legionnaire followed by a Spined Thopter, then I'm almost certainly going to cast my Thundering Tanadon on turn four. The only other plays that could reasonably dissuade me from casting my Thundering Tanadon that early would be if I could cast something like a Blightwidow to stop my opponent's offense dead in its tracks, or something that is comparably powered like a Vital Splicer or, something far more menacing like a Moltensteel Dragon.
Drill Baby Drill
Pith Driller doesn't suffer from the same drawbacks as Thundering Tanadon. If I'm playing against an aggressive deck, then I absolutely want to draw my Pith Driller, and it'll usually be just as good when I'm going second as it would be if I were on the play. Even if my opponent gets off to a really fast start, I'll be able to set him or her way back by tossing down a 2/4 blocker and offing a creature that would otherwise spend the next few turns pummeling me.
Yes, a single Pith Driller can stop an aggressive start dead in its tracks. Follow that Pith Driller up with a Rotted Hystrix,or a Reaper of Sheoldred and your opponent might not be able to get through on the ground for another four or five turns.
So while there are going to be situations where paying 2 (or 4) life to cast a Phyrexian-mana spell will put you in a lot of trouble (particularly if your opponent has a removal spell at the ready), there are also going to be plenty of times when you will be able to get back into games that you might otherwise have no chance to be a part of because you are able to cheat a bit on mana by paying life to help cast your spells.
How do you know whether you're in a situation where paying that life will be just the first step towards digging your own grave, or whether it'll be enough for you to dominate your unsuspecting opponent? Well, you're going to have to use your own good judgment to figure that out.
If you realize that you're probably going to lose if your opponent has a removal spell for your Thundering Tanadon after you paid 4 life for it, then you should probably hold off on casting it. But if you realize that your opponent is probably going to beat you if you don't do anything impressive quickly (regardless of whether he or she is holding a removal spell), then you should be rushing to drop your big creatures or your board-stabilizing Pith Drillers as quickly as possible.
It's Almost Prelease Time!
Four days and counting... Are you ready?