(Reposting to fix several bits of bad coding. Never HTML when drunk, people.)
I'm not entirely sure why, but this episode did not really seem as appealing to write about as others. I suppose that even though it had a great deal of future plot points introduced, the actual episode itself was not, well, dramatically charged or otherwise compelling. It was one step up from filler, so to speak. (Note that I have absolutely nothing against filler, and indeed, in some cases, prefer filler to actual plot.)
Anyway. Episode 12 of Card Captor Sakura, "Sakura's Never-Ending Day", deals mainly with one of the basic truths of the universe, being Time. Experience with playing a Time-focused character in Mage: The Awakening implies that it is a tremendously powerful ability (I mean, seriously, it's near-broken), but also quite draining (I blow Mana points like water). This matches up quite well with uses of the Time card in future episodes.
I should also note that I'm finding fewer things to say about this episode as I go on. So if this summary seems less entertaining than usual, well, there's always next time. Or the next one after that, if needed. I do have fifty-eight more episodes and two movies to go.