Draft Queue Bug
If you want to guarantee 2 roles as a trio queue, you can queue up with 2 players picking the same roles in reverse order, and the third picking 2 different roles.
For example, if you want mid/jungle
Player 1: Top/adc Player 2: Mid/Jg Player 3: Jg/Mid
This is a valid queue and will let you find a match. However, if you try queuing with the following combination, it won't let you start:
Player 1: Fill Player 2: Mid/Jg Player 3: Jg/Mid
I'm not sure if this is intentional, but it seems like a bug to me. The second combination actually covers MORE roles, yet something isn't going through. I haven't done extensive testing on this, but have noticed this behavior in normal draft.