Left armer Wanger took five for 64 and legspinner Ish Sodhi three for 59 as they rattled through the second half of their hosts' first innings.
Wagner took three for 22 in 24 deliveries; Sodhi used his height to get bounce and turn for a good return.
No one could doubt Wagner's workhorse qualities.
The South African-born 27-year-old is a bundle of aggression and always looks up for a challenge. He walks briskly back to his mark, looks like he means business, and clearly has a pile of energy.
His return last night took him to 29 wickets halfway through his ninth test at an improving average of 36. It makes you wonder why he wasn't picked for the drawn first test.
Sodhi, a 20-year-old in only his second test, still has loose moments but until the arrival of Shane Warne that wasn't unusual in legspinners.
Williamson's injury came after he and Ross Taylor were repairing a poor start in which openers Hamish Rutherford and Peter Fulton departed just before lunch.
Opening batsmen are accustomed to facing fast-medium bowlers when they take their guard. But things don't always happen that way on the subcontinent and Rutherford and Fulton were caught short by classy left arm spinner Shakib al-Hasan.
In trying to avoid a bouncer from lively Rubel Hossain, Williamson was struck a solid blow on the grille of his helmet, just below his left eye.
He had repairs and stitches, and returned when captain Brendon McCullum departed to a daft shot, pulling a long hop to deep square leg where Hossain leapt and grabbed a spectacular catch. McCullum could have hit it anywhere.
The pitch is taking turn, Bangladesh have three spinners and will bowl last. Testing times lie ahead.
Taylor, playing his 50th test, worked hard, cutting strongly and driving efficiently.
He was beaten a couple of times but it was a day for taking care on a pitch which in ensuring the bowlers are always in the contest.
