It's one of my favorite spells in the game, but that might just be nostalgia clouding my judgement. Life as a lowbie Sorc sucked for me until I had High Miasma, and then I started feeling powerful. The cast time on it too seems pretty good for what you get. Sometimes I keep it even after I have all of the higher level abilities unlocked, but sometimes it's hard to decide, especially if you're either the only caster, or just impatient when it comes to buffs.
My Sorcerer usually has:
High Comestion
High Levin (I don't like Brontide on a Sorc, and Fulmination was too specific, but I think it will work pretty well in BBI)
Affinity of some type (Usually Fire > Holy, but Ice for drakes and Dark for one fight)
High Exequy or High Voidspell (although eventually it's kind of useless compared to just using panacea and it doesn't remove curses like the description makes you think it would)
High Frigor (I use Gicel on drakes, but not much else)
High Bolide or Maelstrom just depending on what I'm in the mood for and the location.
At that point Miasma just gets used in the more cramped dungeons when enemies are either really clustered, or they don't have a specific weakness to abuse easily. But it's not that often. I have never been able to justify Seism, although some swear by it.
It's also arguably one of the best (if not *the* best) at killing Ur when using Hunter's Bolt.
My sorc goes a completely different route. I stay far away from status spells because I find them mostly useless. The whole point of my sorc is to cast big ass spells.
Holy Boon The single best spell in the game. Combined with focused bolt this is the single best tool for 90% of all situations, and is by far, the fastest Ur-dragon destroying tool. It is homing, piercing, hits multiple times, and fires through walls.
Levin Because the other two lightning spells involve putting my sorc in harm's way, so they are pointless. Great for gore orges, living armor, sirens, gargoyles etc.
Voidspell Cures all statuses the Mage's Halidom does not. Perfect for BBI where all sorts of rare status effects in vanilla become common.
Bolide Covers large areas, destroys mobs, looks awesome. The actual impact has a physical damage component as well, and works against golems. It also destroys living armor, and most importantly, death.
Gicel Can be aimed and has a deceptively long range. It's amazing when using this to shoot down a swooping griffon using free aim. It also has a physical damage component. Can instant kill gorechimeras.
Maelstrom or Seism Maelstrom works best in the large open spaces in vanilla, enemies who have been caught in a high maelstrom cannot recover fast enough to escape a second maelstrom. Seism is mostly situational. Even though it is holy it's not useful against the Ur-dragon, but works great against Daimon.
To abuse the spell synchrony I always pick a 2nd sorc with similar spells. And I also have a mage to cover with anodyne and halidom.
