Regulus actually plans his mines, uses them as grenades and tries to retreat over them to damage chasers, I actually saw him throw mines in the opposite direction, run past them and stand there pelting me so I'd come over and run over them.
THey tend to have more problems with towers though, running in and past them until their health is too low to run back past and such. (They stay there which is pretty cool and also pretty abusable). It's still easy to get them to run away and kill them because they stop damaging you, they should know when to keep attacking because they would've killed me then.
Smarter in some ways, more stupid in others! Impossibles have much better item choice now and are pretty darn hard to kill!