Summarizing what I wanted to suggest,
3rd lvl Haste:
* +1 apr, AC, THAC0, and speed factor (the latter would be a new entry)
* if possible something like +50% movement rate instead of th current +100%
* last 10 rounds
* whole party, but 5 rounds fatigue after it (note that SR's fatigue also affect spellcaster's casting speed factor)
6th lvl Improved Haste:
* +2 apr (finally affecting non-warriors), AC, THAC0, and speed factor
* +100% movement rate
* last up to 20 rounds
* single target, but no fatigue after it
Good suggestions, but here's how I think these spells should more-or-less be :
3rd level haste :
Effect : +1 APR / +50% movement / 5 rounds fatigue after the spell ends.
Duration : 1 round / level up to 20 rounds (Why set the duration to 10 rounds ?)
Affects : Whole party
Basically, same as Vanilla except the fact that speed is only improved by 50% / fatigue uses your (much better) system.
In advanced D&D, haste doesn't grant AC/THACO bonus, but doubles attacks / speed and ages the recipient of the spell
Instead of aging the character, your version (and the one chosen by the developpers) fatigues at the end of the spell.
Haste: [...] When this spell is cast, each affected creature functions at double its normal movement and attack rates. A hasted creature gains a -2 initiative bonus. Thus, a creature moving at 6 and attacking once per round would move at 12 and attack twice per round. Spellcasting and spell effects are not sped up. The number of creatures that can be affected is equal to the caster's experience level; those creatures closest to the center of effect are affected first. All affected by haste must be in the designated area of effect. Note that this spell negates the effects of a slow spell. Additionally, this spell ages the recipient by one year, because of sped-up metabolic processes. This spell is not cumulative with itself or with other similar magic. Its material component is a shaving of licorice root. [2E CD-ROM PHB]
Since the drawback is not as huge, the benefit is much lower, and only grants +1 APR : original version sounded fair... the +1 THACO / +1 AC comes from DnD 3.5, and doesn't really belong here... the spell is powerful enough without that bonus.
Regarding Improved Haste, this is a completely made up spell, so, I'd instead turn it into the following :
6th lvl Improved Haste:
Effect : +2 apr / +100% movement rate / -1 Spell Casting Time
Duration : 1 round / level up to 20 rounds
Affects : Single target
Single target haste, more powerful and more versatile (adds a nifty bonus for spell casters, and the same APR for all classes, better for non-fighter classes).
Granting additional APR & speed is more than enough power for that spell, I really don't understand the reasoning for boosting these spells even more by granting THACO and AC, beside having the spell look more "D&D 3.5-like", which is not what your mod is trying to achieve (?)
These spells were already "bread & butter" of Baldur's Gate I & II before even boosting them. It's like granting bonus to other very powerful spells, like PFMW or Time Stop, or Improved Alacrity & so on..
Another thing that you could do would be to rename the spell into "Alacrity" rather than Improved Haste, and have it grant the same bonus as Improved Alacrity, but for the duration of 1 round, which would make it balanced, I guess ?
Edit.: Forgot PnP haste also grants -2 bonus to initiative, might want to add it if you want to stay true to PnP, but it's not like initiative is *that* important in baldur's gate (?)
Edited by Aranthys, 26 January 2012 - 06:24 AM.