Despite ending his lean patch by reaching three figures the previous evening, Root showed his appetite had not been sated as he recorded his first overseas double hundred and highest score since becoming England captain.
England's 476 all out gave them a first-innings lead of 101 but the reliable pair of Kane Williamson and Ross Taylor took the Black Caps to 96 for two as the deficit was all but wiped out.
While there was some variable bounce at Seddon Park, the benign nature of the pitch and the forecast for rain for much of Tuesday means a stalemate seems unavoidable, which would hand New Zealand a 1-0 series win.
But this should not detract from Root's third double hundred of his Test career - he made 254 against Pakistan at Old Trafford in July 2016 and 200 not out versus Sri Lanka at Lord's two years prior to that.
The 441 balls he faced and 636 minutes he spent at the crease meant this was the longest innings of his career, while he leapt above Wally Hammond and into the top 10 among England Test run-scorers.
A 193-run stand in 62.3 overs alongside Ollie Pope, who contributed a Test-best 75, was the cornerstone of the day, and the pair only perished within minutes of each other when they attempted to up the ante.
But because they started the morning trailing by 106 and had only five wickets in hand, the overnight pair showed caution early on under heavy cloud cover.
A Tim Southee scuttler whizzed past the off-stump of Root, who resumed on 114 and pulled the Kiwi seamer for four from a shorter delivery that did not rise as anticipated.
Pope's first boundary came via an inside edge but he gradually grew in confidence alongside Root, who was more proactive against Mitch Santner than he had been the day before, bringing out the slog sweep as the partnership stretched into three figures.
By this stage, Root had passed 150 while one of the numerous swift cuts from his junior partner gave England a slender advantage at lunch, shortly after which Pope brought up a maiden Test fifty from 165 deliveries.
From thereon in, Root took centre stage in the afternoon session, leapfrogging Hammond in some style as he bisected fielders at point and short third man with a precision cut from a wider Daryl Mitchell delivery.
It was a scampered single which took Root to 200 from 412 balls following a push into the offside but Pope's initial hesitancy would have seen him run out had Henry Nicholls connected with the stumps from cover.
Root advanced down the track and creamed Matt Henry for a sumptuous straight six - his only maximum to go with 22 fours - which heralded a more adventurous approach from the Yorkshireman and Pope.
England's expediency may have been with Tuesday's weather forecast in mind but it led to the downfalls of Root and Pope within five balls of each other, the latter pulling Wagner high to deep midwicket.
In the next over, Root's stay of more than 10 and a half hours at the crease came to an end when he attempted to go inside-out against Mitch Santner, only to hole out to deep cover, walking off the pitch to a standing ovation.
Neil Wagner cleaned up the tail, angling one across Chris Woakes before bowling Jofra Archer and Stuart Broad with slower deliveries, to finish with five for 124, impressive given his leg took the brunt of a full-blooded drive from Root earlier.
England lost their last five wickets for 21 runs in the space of 37 balls but had a lead of 101 heading into the final session, where Sam Curran was preferred to Jofra Archer with the new ball.
Curran vindicated the decision by pinning Jeet Raval in front, the opener walking straight off despite replays indicating a thick inside edge on to his pad, before Woakes found a bit of nibble to have first-innings centurion Tom Latham caught at first slip.
Archer's eventual introduction saw him clatter Williamson on the arm guard but the New Zealand captain (37no) and Ross Taylor (31no) avoided any further alarms.