if Voldy truly mastered death he would've been unfukkable, but some of his traps for the horuxes were ill...the locket one, the one at the bank (book version was better, cause shyt would burn you). He really didn't have a plan per se when he got back though...he just wanted to chill and kill muggles. If he really wanted to expand beyond to overseas, he might've been able to pull it off