Two Minor Flaws
We have a plan to catch the tiefling bandits before they strike again, and this time we've done our homework. We've researched what we know about tieflings and that they have an ability that acts like the darkness spell. We've talked to some vagrants in the decrepit part of town who've seen the tieflings wandering around, to get an idea of their numbers and what paths they use. We've reconnoitred the area around their base of operations and found tracks suggesting which route they take before diverting to a specific point to cross in to the city proper. A suitable building has been found where we can lie in wait for their next excursion, and we've got some silent signals prepared to get us all ready when they are spotted coming our way. For once, we're prepared. It feels unnatural.
Our luck is in, as the tieflings move out of their base on the first night we wait for them, although another attack was due according to their modus operandi. Afutavere, our elf, sees them coming and taps our bard with the first signal, telling him to get ready. When they are close, he gives the second signal, and Brennan casts his light spell, giving us plenty of illumination to attack the tieflings, and we launch out of our cover. It's all working as planned! And then the tieflings cast darkness, and they are thrown in to a magical blanket of blackness, giving them complete cover that our normal sight cannot penetrate.
'Can they do that?'
'Um, yeah. I suppose we found that out earlier.'
'So what do we do?' It's a good question, as crossbow bolts coming pinging out of the darkness with more accuracy than we could manage firing them back.
'We're just going to have to do our best. Charge!' Paladin Ganelon rushes in to the lack of light and swings where he thinks a tiefling should be, his sword slicing only air. For his troubles he gets a short sword jabbed back at him. 'Argh! I'm being attacked, to my left!'
'That's great! Where are you?'
'And which direction are you facing?' Okay, vocal cues aren't going to help us either.
Afutavere pulls his bowstring taut and readies an action 'to shoot any tiefling I see.' That's the elf giving up on combat, apparently. And with more crossbow bolts coming our way and the paladin getting stabbed a couple more times the bard marks our retreat by running very fast away from the tieflings. The rest of us follow.
I'm sure even the admirable Kryten would admit ours was an excellent plan, with just two minor flaws. One, we learnt about the tiefling's darkness but didn't do anything to account for it, and two, we learnt about the tiefling's darkness but didn't do anything to account for it. Now of course, technically speaking, that's only one flaw but it's such a big one it's worth mentioning twice. Maybe we need to think about this some more.