You'll notice the Illithid powers really evolve throughout your journey, and there's a good reason for this - the more you use the tadpole, the stronger its influence becomes (this mirrors your character's growing connection to these abilities). Starting out, you're mainly dealing with simple mind-reading checks that help in basic conversations, but don't get too comfortable because things ramp up significantly.

Around the middle of your adventure, these powers become much more interesting, since your tadpole's influence has grown stronger (worth noting that using the Zaith'isk item here can give you a nice advantage). The checks get tougher but more rewarding, and you'll start seeing how they can dramatically change certain conversations and outcomes.

When you reach the later stages, that's where things get really intense - we're talking about checks that can completely alter your story's direction (some requiring nearly impossible DCs of 99). Your companions will definitely have strong opinions about your choices with the tadpole by this point, and those reactions matter more than you might think. A really interesting thing to keep in mind is that these powers can permanently change how your character looks and how different factions treat you (might want to save before making major Illithid-related decisions, just to be safe).