Mint seals off the flow of Mana from Yggdrassil in the ending to keep the tree from being depleted and killed as it was in the original timeline. Seems like a good idea right? It's said that people (and presumably everything else) can survive without Mana, just as they did before, although magic will disappear. Fair enough. But what about the Spirits? The ones that spent the whole game helping you? Aren't they MADE of mana? The whole plot seems like enough of a senseless tragedy without the heroes blithely dooming them as well. No wonder Origin thinks humans are morons. Sucks a bit for the elves too, who've been using magic responsibly for ages
"Mint seals off the flow of Mana from Yggdrassil in the ending." Uhh, no she doesn't. In fact, if she did, that would be counterproductive to Martel taking a giant clump of mana (and, depending on which version of the game/OVA we're talking about, maybe even her own soul), turning it into a new Yggdrassil Seed, and shipping it off to OUTER SPAAACE so it can restore Cybertron I mean Derris Kharlan to its original glory.
I always interpreted it as the barrier being like a filter so that enough mana to maintain various things were released, but not enough for magitech to deplete it to such a level that the tree would die of it.
Ratatosk says exactly the opposite. Spirits are not native to Aselia and because of this still need mana. This is why Sylph asks you to look for a reason for the mana shortage as a condition of her pact!
Ratatosk pulled some strings with the laws of reality, changing things so that mana was no longer essential for all life (this is why the death of Yggdrassil does not cause the world to end). This results in the World Tree to function without too much trouble, creating mana for the things that still need it. The proto type magitechnology, however, was very inefficient, sucking in vast amounts of mana, straining the World Tree, causing mana shortages. Anyway, getting to the point, it's likely that Mint seals the World Tree so it can recover, grow stronger, and be able to produce mana without killing itself. When it does, Mint will probably unseal it.
Was it ever ever even explained why Dhaos really needed the mana seed? It appears that Cless's world survived after the death of the world tree so what exactly is going on in Dhaos's home world?
Explained or at least hinted at in the prequels. While the planet the games take place on is made of ordinary matter with mana as a supplemental force, Dhaos's world of Derris-Karlahn (technically a large, inhabitable comet) is made entirely out of solid mana, and is what brought the first mana tree to the games' planet in the first place. If it lacks a mana generator, the comet/planet will presumably be consumed over time by usage, decay, and upkeep of magical beings. On the games' planet, a lack of mana production means the magical beings and spells die off, whereas on a world made of the stuff, a lack of mana production means the planet will be consumed first.
If in the original timeline, the tree died and magic couldn't be used...How is Morrison able to cast Indignation in that infamous opening scene exactly? (And for that matter, how do clerical artes even work?)
Because while the tree was withering because of the Mana Cannon, it didn't died right away, and there was still mana around, allowing for magic to still be used. Not to mention that the Dhaos fight in both versions of the time line happened just shortly after, so it wasn't enough time for the tree to die. In fact, one of the first things to do after is to save the tree. Meanwhile, clerical artes seem to come from a different source, which is why they can still be used even with mana gone.
The clerical artes/divine power are never fully explained (which Headscratchers, as I'm sure it does others), but I always imagined it was basically Mint/other nameless practitioner using a part of their own respective beings to patch up someone else. Basically, they rip off a piece of their own kindness and make it into a magical band-aid.