So I run a Zada, Hedron GrinderSilverfur Partisan deck with the goal of making a bunch of 2/2 wolf tokens, then finishing off with a Confront the Unknown to swing for a massive amount of damage. If during my combat, my opponent casts a spell to prevent all combat damage, and I then move to my second main phase an cast a Aetherborn Marauder, moving all +1/+1 counters to him, would he retain those counters after my end step? I think I'm right in saying he would, since Confront the Unknown only really states the target creature gets the +1/+1 counters.
Confront the Unknown does not grant +1/+1 counters. It gives a creature +1/+1 equal to clues until the end of turn not a +1/+1 counter.