Roy smashed 78 from 44 balls as England cruised past the previously unbeaten Black Caps, with Root finishing unbeaten on 27 as Jos Buttler thumped a series of sixes to secure victory.
While Root is currently England’s leading scorer at the tournament with 195 runs, Roy is not far behind with 183 and the Yorkshireman admits his team-mates destructive capabilities make him one to watch against the West Indies on Sunday.
“There’s a mixture of disbelief and a wow factor he brings to the team,” Root told ecb.co.uk.
“Some of the shots that he plays – it’s astonishing that he can pull that out the bag in a semi-final.
“It takes a lot of pressure of you when you’re waiting to bat and you’re seeing the scoreboard always ticking over and you’re always ahead of the game.
“Hopefully he can do something special again in the final and we can go one further.”
Buttler finished with 32 from 17 deliveries and Root is equally impressed with the wicketkeeper-batsman’s ability to bat the opposition out of the game in double-quick time.
“You feel he can do it at any time,” added Root.
“When we were out in the middle I was trying to keep things calm and said ‘let’s just tick it over five at a time’. He said ‘don’t worry about that, leave it to me’ and did his thing that he does so well.
“It’s great to bat with because you always feel that you’re two shots away, even if you’re behind the eight-ball, of being right back in control.”
England skipper Eoin Morgan was particularly pleased for Roy, whose semi-final knock was his first T20 International half-century.
“There were probably a couple of moments where we were sitting watching and absolutely amazed by everything that was going on – Jason Roy’s innings for instance was unbelievable,” he said.
“One of the best I’ve seen certainly in white-ball cricket. His first fifty in an England shirt and what a day to pull it out of the bag.
“I thought the array of shots that he showed against one of the best bowling line-ups in the tournament was outstanding.”