Awesome!
Though it would be cleaner if it just became a 4/4 human soldier creature and did not remain a planeswalker.
+1: Put a blink counter on target creature.
Creatures with blink counters on it have "If this creature would be put into a graveyard from play the battlefield, exile it and return it to the battlefield under its owner’s control instead at the begining of the next end step ".
fixed

+1: During target opponent's turn, creatures you control have Hexproof.
should probably be:
+1: Until the begining of your next upkeep, creatures you control gain Hexproof.
new addition:
-2: Until the begining of your next upkeep, you gain Hexproof and creatures without flying cannot attack you. (too powerful?)
My vision of your Venser, the Caretaker:
+1: Until the begining of your next upkeep, creatures you control gain Hexproof.
+1: Put a Blink counter on target creature. Creatures with Blink counters have "If this creature would be put into a graveyard from the battlefield, exile it and return it to the battlefield under its owner's control at the begining of the next end step"
0: Until end of turn, Venser, the Caretaker becomes a 4/4 Human soldier creature with Intimidate.
-2: Until the begining of your next upkeep, you gain Hexproof and creatures without flying cannot attack you.
2