This concerns the part of Chapter 3 called 'Stones of Dominion'. Specifically, shortly after you are asked to find the triplets and have learned the words to summon the Taifelel in a supposedly weakened form. You learn the words from Feodor but just in case you can't remember them by the time you need them, here they are:

• Malkor
• Mashrak
• Maragosh
• Zidjan
• Taifel
• Marashik
• Marak
• Marak
• Mharatai

To be honest, I didn't find the summoned beast particularly weaker; it still spawned the annoying woodlice and the reward didn't seem too special either, but for anyone who wanted to try it out themselves but couldn't remember the incantation, hope this helps! :)