Anscombe has been out of action since injuring his ankle in the Rugby World Cup quarter-final against South Africa in October.
But the 24-year-old is now fully recovered and takes his place amongst the replacements for the big clash in London as Cardiff Blues come up against an undefeated Quins team who top the pool.
Head Coach Danny Wilson knows victory is vital in England and makes just two changes to the starting line-up that defeated Scarlets in the region’s last competitive game.
Prop Sam Hobbs comes into the front row, with Gethin Jenkins ruled out of the game with a neck injury as Lloyd Williams takes on the captaincy.
The other change is a call-up for versatile forward Macauley Cook into the second row to partner James Down.
There is also a welcome return for fit-again back row Ellis Jenkins who is named among the replacements for the European clash and who will make his 50th
appearance for the region if he comes off the bench in the English capital.
Head Coach Danny Wilson said: “It’s a game between two sides in form. Quins have been going well and some of the rugby they have played in difficult conditions is impressive. The squad that they have got gives them the depth and the ability to do that.
“There is no doubt that Quins have match winners all over the park and their squad is impressive. To be bringing the likes of Jamie Roberts in at this stage of the season has given them another dimension too.
“We know the challenge of going to Twickenham Stoop to get a must win result, but that is exciting and that we are still in a position to qualify is something we must look to take advantage of.”
Cardiff Blues: 15 Dan Fish, 14 Alex Cuthbert, 13 Cory Allen, 12 Rey Lee-Lo, 11 Tom James, 10 Rhys Patchell, 9 Lloyd Williams (c); 1 Sam Hobbs, 2 Kristian Dacey, 3 Taufa’ao Filise, 4 Macauley Cook, 5 James Down, 6 Josh Turnbull, 7 Josh Navidi, 8 Manoa Vosawai
Replacements: 16 Ethan Lewis, 17 Thomas Davies, 18 Dillon Lewis, 19 Jarrad Hoeata, 20 Ellis Jenkins, 21 Tavis Knoyle, 22 Gareth Anscombe, 23 Gavin Evans