The 19-year-old, who featured for Wales U20 last season, made his debut for the Dragons aged just 17. He comes into the side to line-up in a back-three alongside British and Irish Lions duo George North (Northampton Saints) and Leigh Halfpenny (Cardiff Blues).
In the midfield Ashley Beck (Ospreys) makes his first start of the Dove Men Series after featuring from the bench in the opening two games. He is joined in the centre by Cardiff Blues' Owen Williams who will earn his third cap after making his debut on the summer tour to Japan.
Perpignan's James Hook has been named at fly-half alongside Lloyd Williams (Cardiff Blues) at scrum-half.
There are six changes in the pack from the side that beat Argentina by a record margin last weekend.
Bath prop Paul James and Scarlets hooker Ken Owens come into the starting-line up to join Rhodri Jones (Scarlets) in the front-row.
In the second-row Luke Charteris (Perpignan) starts for the first time this autumn and will play alongside British and Irish Lions second-row Ian Evans who returns from injury to take his place in the side.
Justin Tipuric (Ospreys) retains the number seven jersey and is joined in the back-row by Andrew Coombs, who features for the first time in the series. Ryan Jones (Ospreys) lines-up at number eight and the record holding captain will lead Wales for the 33rd time on Friday.
It is the first time in twelve years that Wales welcome Tonga to the Millennium Stadium and Warren Gatland, who will reach the milestone of 100 international tests as a head coach on Friday, is expecting a tough encounter.
"Tonga are a typical south sea island side and will be physical, powerful and won't take a backwards step,” said Gatland.
"We pride ourselves on matching other side's physicality and we will have to do that on Friday.
"It should be a great encounter with both sides looking to move the ball around.
"We have made a number of changes but it's a great opportunity for these guys to show us exactly how they cope with the international game.
"The whole squad has trained well since the start of the campaign and they deserve their chance.
On the replacements bench Wales have called Wales U20 and Scarlets back Jordan Williams into the squad for his first taste of international rugby at senior level. He is joined by Ospreys prop Ryan Bevington and Scarlets hooker Emyr Phillips who made his debut in Japan in the summer. Samson Lee who won his first cap against Argentina is again on the bench. Uncapped scrum-half Rhodri Williams (Scarlets) lines-up alongside regional half-back partner Rhys Priestland
WALES TEAM v TONGA:
Leigh Halfpenny (Cardiff Blues), George North (Northampton Saints), Owen Williams (Cardiff Blues), Ashley Beck (Ospreys), Hallam Amos (Dragons), James Hook (Perpignan), Lloyd Williams (Cardiff Blues), Paul James (Bath), Ken Owens (Scarlets), Rhodri Jones (Scarlets), Luke Charteris (Perpignan), Ian Evans (Ospreys), Andrew Coombs (Dragons), Justin Tipuric (Ospreys), Ryan Jones (Ospreys - CAPT).
Replacements: Emyr Phillips (Scarlets), Ryan Bevington (Ospreys), Samson Lee (Scarlets), Dan Lydiate (Racing Metro), Sam Warburton (Cardiff Blues), Rhodri Williams (Scarlets), Rhys Priestland (Scarlets), Jordan Williams (Scarlets).
