Gimping Great Haste

Great Haste is a very nice spell.  For 10 seconds (read as: one combat), you get two maneuvers per turn.  And the second maneuver determines active defenses, which means that you can basically All-Out Attack without penalty on the first maneuver.  (Unless a nearby opponent with a Wait can interrupt.)

Drawbacks: 3s casting time, 5 FP cost to both caster and subject.  Of course both the casting time and mana cost can be reduced with high skill.  And all casting times can be shortened by the caster self-Great Hasting first.

It gets really broken when you have a caster with Great Haste-25 that self-hastes on the first turn of combat (or, better yet, right before combat starts, though this requires knowing that combat is about to start), then hastes the whole party, two per turn.  Buff mages are amazing in GURPS.

The real issue is that it's multiplicative: your casting skills multiply someone else's combat skills.  (It wouldn't be as broken if you could only haste yourself, since all the points you spent to get Great Haste-25 means you're not so great at non-IQ non-spellcasting things.)  Great Hasting a vanilla weak fighter with one attack per turn turns that into two.  (Or three, if they All-Out Attack (Double) on the first maneuver.)  But Great Hasting someone who has Extra Attack and Weapon Master so they can Rapid Strike can give someone enough maneuvers for the rest of the players to fall asleep while you execute their turn.

How to make multi-player games fun: keep each player-turn short.  How to make multi-player games awful: make one player's turn last forever, so the other players tune out and then aren't paying attention by the time their turn comes up.

Anyway, my current fix to Great Haste:

PCs are limited to three attack rolls per turn, from any source.  Feints count.  Great Haste is still useful for doing other things like fast movement, or for getting characters without extra attacks up to 2 or 3, but it's not useful for turning a fast attacker into a cuisinart.

There are probably more elegant fixes, but this one is dead simple.  I hate changing house rules in mid-campaign, but I hate quitting campaigns because they're not fun even more.


Other options I considered:

AD&D first edition's Haste spell aged the recipient one year, guaranteeing that the spell would be used fairly rarely (at least on humans without magical fountains of youth).  But since long-lived PC races and anti-aging magic exist, I don't think this is enough.  (Then you need to start charging elves and dwarves more points for longevity if it's actually useful.  Or make the aging proportional to lifespan.)

Make the two maneuvers non-consecutive, eliminating the risk-free All-Out Attack.  Or, patch All-Out Attack to always eliminate all your defense rolls for one turn.  Either works to eliminate the cheesy AoA on the first maneuver of a Great Hasted turn, but I fear that's not strong enough, as Great Haste is still too good even without abusing AoA.

Gimp wizards generally.  Limit Magery to 3, worldwide Low Mana Zone, base spell skills on 10+Magery rather than IQ+Magery, reduce FP cost / casting time bonuses for high skill, etc.  There are many options, but it's tricky to get the balance right so that people are still willing to play wizards but wizards don't rule the world.  I felt this was way too much to do in mid-campaign with a live wizard PC in play, though.