Semi-Ablative was introduced in 4e as a limitation to Damage Resistance. It is worth a lower % reduction than Ablative.
It actually functions the way Ablative did in 3e according to the Ablative DR guidelines in GURPS Robots as http://www.sjgames.com/gurps/faq/FAQ3-9.html#ss9.3 explains.
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re Armor Divisor[]
2008 where reference is made to Kromm having previously addressed it...
2007 http://forums.sjgames.com/showthread.php?t=24126 PK replied:
- TTBOMK, an armor divisor has no effect on the Ablative or Semi-Ablative limitations. If you rolled 35 points of damage, then that's what you use to determine how much DR is lost.
2010 still asking Q though http://forums.sjgames.com/showthread.php?t=73330
2017 edit to 2011 post http://forums.sjgames.com/showpost.php?p=1223196&postcount=36 references 2013 post http://forums.sjgames.com/showthread.php?p=1652915#post1652915 which has comparison:
- With 2d+2 pi++, you'll average 9 points of damage per second. You'll need 10 seconds to ablate DR 90, leaving DR 6. On the 11th second, you'll put 3 points past DR 6, which will inflict 1 HP, and also ablate down to DR 3. Then you'll be putting 6 points per second past the minimum DR 3, inflicting 3 HP per second, for the next 26-27 seconds. Total time: 37-38 seconds.
- With 2d+2(2) pi++, you'll average 9 points of damage per second. But now DR is halved! You'll need five seconds to ablate DR 45, leaving DR 3. Then you'll be putting 8 points per second past half the minimum DR 3, inflicting 4 HP per second, for the next 20 seconds. Total time: 25 seconds.
Vicky molokh also quotes it in http://forums.sjgames.com/showthread.php?t=148403
2014 in http://forums.sjgames.com/showthread.php?t=130214 Nereidabel interprets this as Corrosive w/ AD depleting better