As I understood it, they each used their strongest Genjutsu because, as you say, it was mortal peril. Perhaps that scale of genjutsu was needed to defeat Kabuto's Genjutsu. Kabuto's technique may have been enhanced by Sage Mode.
Originally Posted by Ahmad Jamal
Anyway, Edo Itachi has far, far more chakra than Itachi's ever shown in life. He was weakened when he fought Sasuke, and may have been overstating his fatigue against Kakashi/Guy for the sake of avoiding conflict, but he's still using way more techniques. Consider this to be in line with every character these days... Kakashi has been shown fighting multiple Jinchuuriki, even after his all-day Rampage. Sasuke seems to double his chakra capacity every time he fights; look at him against Itachi, and then against Danzou. Kishi sortof bends the rules, especially when stamina is involved, for the sake of making his fights get progressively more exciting.
To be fair, I think it does Kabuto an injustice. Kabuto's biggest advantage over the Uchiha bros is his Sage Mode chakra capacity. If they were as easily-drained as usual, he'd have already won. But apparently sitting in Susano'o for 5 chapters while spamming Amaterasu and Tsukuyomi is easy for Sasuke/Itachi. I'd expect it to be a natural part of Sasuke's EMS power-up, but in Itachi's case this is simply unfair.
That said, we rarely see any Edos run out of chakra.
Don't think we've seen any edo run out of chakra.
Pretty much. Seeing as Kabuto and Oro were researching Sage Mode and natural energy, it's possible that it lead them to ET, which perhaps replenishes Zombi's chakra (by converting natural energy in to spiritual and physical parts ?). The only time an Edo couldn't cast his jutsu, was not because he couldn't refill his chakra, but because his capacity (in other words, the amount he can keep stored at one time) was halved.
Originally Posted by Kenny Bones
Yeah, you're talking about Muu right? Indeed. One can only assume that chakra storage is and has been a huge deal to any shinobi. So it's only logical that Orochimaru researched it. And also, since we now see that edo Madara and edo Itachi seems to have unlimited chakra, something's definitely up with that.
Also keep in mind this is Senjutsu enhanced Genjutsu specifically designed to counter Uchiha. Kabuto has been planning to take Sasuke for some time and has been making preparations for the confrontation.
Was it actually specifically designed to counter Uchiha? It was used against Shikamaru pre time-skip (as was shown in this thread) and I can't remember if it was then also specifically designed to counter Uchiha. Also, I gotta say that I don't see any indication that every technique used while in sage mode is necessarily enhanced by sage mode.
Originally Posted by POW
If a shinobi makes a sandwich while in sage mode, is it extra tasty?
Edo's seemingly burn through a limitless supplies of chakra; making us think they can't run out. They do not have an unlimited supply but rather the caster of edo most likely determines the amount when performing the technique or is allowing natural energy to be converted to the edo subjects' chakra. Just making educated guess, mind you. I wager also why the First Hokage was so unimpressive and short of his reputation when fighting the Third was partly because Orochimaru could not match the First's Chakra amount and capacity when casting that particular edo tensei. The potential of a shinobi is most definitely changed when being revived through edo tensei as shown by a lackluster First Hokage (Orochimaru's standard edo tensei) and the tweaked and improved Madara (Kabuto's leveled up/probably sage mode enhanced edo tensei). I don't believe in truly unlimited chakra, even if edo tensei puts forth remarkable examples of the seemingly impossible.
If he/she/it (theoretically, beside being a plant, Zetsu is a shinobi as well ;P) is utilizing chakra and chakra based techniques to make that sandwich, then yes, it should be more perfect, closer to what the creator was aiming for.
Originally Posted by knife eater
The main point of sage mode is that it adds a new part to the mix (the natural energy), which in turn rises quality and quantity of chakra and thus all chakra based abilities (kekkei genkai as well, since only shinobi have it and they are based on chakra one way or the other).
Sage mode has other benefits as well.