Assuming a Legendary Creature, with regular Adventure.
When you cast the card from the Command Zone, you would have the choice to cast it either as an Adventure, or as a Creature. Either way, you will pay any applicable Command Tax. If you choose Creature, it behaves like a normal Commander, obviously.
If you choose to cast it as an Adventure, you will have the choice when it resolves as to whether to Exile it (via Adventure), or Command Zone it (as it's a Commander). If you Exile it, Adventure then lets you cast the creature half from Exile as normal (and no tax applies). If you Command Zone it, you could cast either half again, but note that the Command tax will be applicable again (and will have gone up).
This also does funky things with how you pay the tax. If the spell half is cheaper than the creature (image a card with an extreme disparity for sake of example, Adventure costs W, and the Creature costs 5WW), you can essentially always use the spell half to split the Commander cost into more manageable pieces. With the example given, you could cast the adventure half for W, then 2W, then 4W, etc... all while your 7 cost Commander remains at 7, allowing you to continue to play your high cost Commander even on a low land count.
The opposite side has a bit less of that problem, but then you run into deck designs that try to bounce the Commander back to hand to replay the spell (especially if the high-cost spell is powerful). If the combo should be disrupted, the deck is able to replay the creature half cheaply to bounce back to hand and start over. No Adventure card actually has enough value to actually encourage this... but who knows.
So, if the spell half is too strong, you could simply end up having a spell in the Command Zone that costs 2 more to cast each time. If the spell costs less than the Commander, you can get into interesting situations where the split Command tax can make deferred payments easier.
My guess is that they didn't want to tackle the "having a spell as a Commander" just yet, though Adventure seems like a way to do it.
JovialJovian wrote: ↑4 years ago
The question would be if the commander tax is applied to both the legend and the adventure, or if it is separate since they are differently named spells. You could argue that they are different spells in the manner of Partners, and that you would track two taxes for them. Or you could argue that they're one card, and that the tax is applied per card, not per named spell. I'm definitely of the latter opinion, that one tax would accumulate for the card regardless of which part you decide to cast.
Yes, the way the rules are currently written, whichever side of the "Commander with Adventure" you cast - if you cast it from Command Zone, would increase the Tax.
The Commander is the card itself, and this includes both 'halves'. Alternate costs still each apply the tax. You do raise the point that this could be initially confusing to a new player, but I don't think it's a lasting or complicated confusion.