New Zealand coach Gary Stead wants left-arm spinner Mitchell Santner to be more "attacking" with the ball if he is picked in the playing XI during the two-match Test series against Pakistan, starting December 26. 

Santner was on Tuesday (December 22) selected in Black Caps' 13-man squad for what are their final round of World Test Championship fixtures. 

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The 28-year-old, who last turned up in Tests on the previous winter's tour of Australia, has received the nod ahead of fellow left-arm tweaker Ajaz Patel. 

The selectors haven't taken any risk with Patel as he has just recovered from a longstanding calf injury. 

"We know that Mitch in white-ball cricket has been a fine bowler for us," Stead told reporters in a conference call, as quoted by Reuters.

"I think what we're looking at is how he keeps being an attacking force in red-ball cricket as well. He's trying to get a bit more drop on the ball."

Seen predominantly as an all-rounder, Santner averages 25.55 with the bat and 44.71 with the ball after 22 Tests in his career so far. 

"If Mitch does play he'd likely play in that number seven (batting) position," Stead said. "The key thing was the balance of the team we are looking for."

Santner will be competing directly for a spot against another all-rounder Darl Mitchell, with the Kiwis highly unlikely to break their robust four-pronged pace attack in home conditions after the emergence of Kyle Jamieson. 

"We would be unlikely to break up that four-pronged bowling attack," Stead said. "If we are going down that lineup it was more about the ability to bat seven for us."