Game v1.1.11. Scavenger difficulty. Observed and repeated during random encounter with apprentice necromancer and 3x zombies.
Character affected is a level 4 Shadowcaster Rogue wielding two shortswords and has the Twin Blade feat. Shield spell was selected at level 3.
The rogue is level 4, and is defending against a melee attack that exceeded AC by 0-2.
No reaction prompt to use twin blade occurs as long as the character has available lvl 1 spell slots.
What is interesting about this is that when the attack occurs there is the message in the combat log saying that shield reaction could not be cast due to not meeting somatic requirements. This is obviously expected (the shadowcaster does know the shield spell but does not have a free hand to cast), but I should still get the twin blade reaction as far as I am aware.
However, if no spell slots are available (all used), then the Twin Blade reaction does trigger.
So it seems to be something with the shield reaction being checked (even if unable to be used) that is blocking the Twin Blade reaction from triggering.
Also repeated test with somatic requirements turned off in difficulty. In this case, Shield would trigger (as expected) and could be used, but if it was not used there was no follow up prompt to use Twin Blade instead. However, again once all uses of shield were expended, Twin Blade would trigger as expected.
Finally, also tried a level 4 green mage with dual daggers who also knew Shield and had Twin Blade using one of the test dungeons. Same behaviour was observed.
The reaction logic seems to take into account whether or not using the reaction will change the outcome (i.e. turn the hit into a miss). When this happened, was the roll within the limits there? The feat makes it so you get a +3 on the 1 attack, IIRC so it wouldn’t change the outcome unless the hit was 1 or 2 over your AC.
Yes I was specifically taking note of cases where the attack roll (+bonus) only exceeded the characters AC by 0-2, so within the range where Twin Blade should be able to block the attack. It was in these cases where the described bug was observed.
Interesting. I’ve also it inexplicably not offer to cast Shield and instead Uncanny Dodge kicks in. But I haven’t been paying super close attention to the dice rolls, so that may have been right. Hopefully they can reproduce and fix!
Ok so I did some further testing to look at Raise Shield and Uncanny Dodge as well, using four new characters and the Party Test Dungeon.
All characters were levelled up to 4 to get either Twin Blade or Raise Shield, except the rogue went to 5 to get Uncanny Dodge.
Char 1: Oath of Devotion Paladin. Sword and Shield (AC 20), has Raise Shield
Char 2: Draconic Sorcerer. Dagger and Shield (AC 18), has Raise Shield
Char 3: Shadowcaster Rogue. Dual Shortsword (AC 15), has Twin Blade
Char 4: Greenmage Wizard. Dual Dagger (AC 14), has Twin Blade
Al characters know the Shield spell.
Basically I just let enemies hit all the characters repeatedly, and just use potions and healing to prolong the fight.
Observations:
While spell slots remain, no character ever received the prompt to use either Raise Shield or Twin Blade.
I kept a log of attack rolls and this included attacks that only exceeded AC by 0-2 on all characters, so within the range where Raise Shield and Twin Blade should have an effect.
The rogue did get the reaction to use uncanny dodge whenever an attack hit.
After ensuring that the test case (attack roll within 0-2 of AC) had been met for all characters a couple of times, the character was then swapped to secondary slot which had a free hand to allow casting of spells. From this point, reactions to cast Shield occurred as expected. In the case of the rogue, if the Shield reaction was passed, the Uncanny Dodge reaction could still be used (and Uncanny Dodge also triggered on its own for cases when the attack roll was too high for Shield).
Once a characters spell slots were expended, they switch back to there initial weapon set (either 1H and shield or dual wield). From this point, Raise Shield or Twin Blade reactions occurred as expected. In the case of the rogue, if the Twin Blade reaction was passed then the prompt for Uncanny Dodge still occurred (and would also trigger on its own for cases when the attack roll was too high for Twin Blade).
Conclusion:
Raise Shield and Twin Blade reactions never trigger if the shield spell is known as long as spell slots remain to cast it.
Uncanny Dodge appears to work as expected, and doesn't seem to have any with either Shield reactions or Twin Blade reactions.
I salute your attention to detail and thorough research! Hope this catches the eyes of the devs.