My current guess is that nebula will be some sort of cloud-creating/area denial spell.
I have no clue what hasta might do. I suspect it has something to do with movement or traversal since “Hasta” is a word that’s kinda similar to “haste” (and also I can’t imagine this spell having much to do with the Spanish word, “hasta” which means “until”).
hasta is latin for spear, so i imagine it’ll be something like that, perhaps a pinning move
Just wait for full release to drop
nebula has to be a delayed explosion type skill after you’ve made a decently large cloud of magic
Nebula is a Subspace tripmine
Nebula could be either poison magic type cloud but for all magics
Or maybe bursting aura from wom
We had bursting aura before
But it got removed
As did flight
So maybe also bring readded
I see no reason why add back aura that got deleted few months after release
Something similar to it, not the exact thing
hasta is just a roman spear, yeah its just that
what if its like a bolt, kinda like a mixture of javelin and beam
think ultrakill earthmover
ultimate art: sunlight spear!
When theorizing about Nebula I think we should mostly be going off of its original name, “Burst”
I get the feeling that it probably doesn’t have a huge relation or resemblance to nebulae, and was just named that because it’s fancier and differentiates itself from Spirit Burst
Those seem to be locked to anything but mages atm so we can expect something using a lot of magic ! I like the idea of a cloud of magic particles around the user detonating after a while for the nebula spell.
The two terms used to refer to this new rare spell (‘Burst’ and ‘Nebula’) make me think that it’ll be a constellation of blasts spread out (similarly to a shotgun) that eventually slows down and explodes roughly at the same time.
If that is the case, it would be an area-denial tool with delayed AoEs that would increase pressure in arenas, but be useless outside of it.
Keywords to think of: Explosion (Burst), Rapidfire/Many (Burst), Stars (Nebula), Cloud (Nebula).
I call that pulsar/javelin
would be funny if it was basically just the nebula ash of war from the wing of astel from Elden Ring lol.
There is some precedent for moves like this because that one close ranged move from the patrimony works sorta similar. initial hit with an after effect (powder fist also works similarly)
maybe the damage would be flipped; low damage at the start then the explosion does the higher damage
everyone forgets about the Bastard’s Stars AoW 
but nah, I doubt it’d be exactly like that
I think it’d be more like the elden beast’s version where it fires a line which then explodes after a little bit .
either way, I think it would be a pretty decent zoning skill if it is one of these
I mean it’s got the same name but is worse for wearing down boss posture since it has a long windup and travels.
And it’s on a flail which… just suck as a weapon class honestly
Hasta is indeed Mage-exclusive, but Nebula will totally be usable by hybrids, since the level cap will be increasing to 175 at the very minimum.