After exchanging early penalties, Barrett created the first try of the contest, bursting through a gap and drawing two defenders before casually underhanding an one-handed offload to Jackson Ormond who went over to give Taranaki a 10-3 lead.
Despite the pitch being coated with puddles, Taranaki then managed to conger up one of the tries of the year through number eight Iopu Iopu-Aso.
Blunder turned into brilliance as an attempted clearing kick from Charlie Ngatai was charged down, the ball fortunately landing in the hands of Iopu-Aso who started a swift 50 metre move.
After being freed on the wing, Mitch Crosswell managed to offload in a three man tackle to Seta Tamanivalu. Tamanivalu then found Ngatai, with an inside ball back to Iopu-Aso finishing off an early contender for try of the season.
Despite being a man down with prop Mitchell Graham in the bin after a blatant trip, Taranaki increased their advantage, with Barrett again at the core, showing great vision to spot winger Codey Rei alone on the right wing. Barrett's perfect cross kick sat up for Rei to collect and dot down, giving the hosts their 16 point halftime lead.
Otago's first half was summed up by a Fletcher Smith penalty attempt which ended up landing closer to corner flag than the uprights, but their second half turnaround was something special.
Two consecutive tries to replacement loose forward Naulia Dawai off powerful lineout drives cut the lead to 22-20, but it looked like Taranaki may have held off the Otago onslaught when Sean Wainui crossed in the corner to make it 27-20.
However, the Southern forwards stepped up again, Aki Seiuli going over from close range to tie the contest with six minutes to go.
Just when it looked like both sides were set to settle for a share of the points, Otago halfback Kaide Whiting snuck over in the 83rd minute after over 30 pick-and-go phases on the Taranaki line, giving Otago a bonus point win and consigning Taranaki to a third consecutive loss.
Otago 34 (N.Dawai 2, A.Seiuli, K.Whiting tries; F.Smith 4 con, 2 pen)
Taranaki 27 (J.Ormond, I.Iopu-Aso, C.Rei, S.Wainui tries; C.Rei 2 con, 1 pen)
Halftime: 6-22