I went last week for a couple of hours after a day working in the area this is my route.
Start through the big forks down Pinderosa and before it goes up join the blue for some fun in the berms. Cross first road and continue on blue to next road. Go through car park, cross bridge, turn left along fire road to an uphill right before a gate. Follow round to start of Pink Heifer but continue of fire road, go round gate, through wood and cross stream up a short climb to rejoin red route at marker post. Turn left and head round to Hermon.
At the end of Hermon go up the road passing the cafe and up the hill. Turn right at the sign onto fire road, at next junction left to road, then right and right again back onto fire road to start of Adams family descent.
After the descent you can either repeat Hermon/Adams or go back to Adams by going towards PH but bear left and up the fire road, at Junction turn right and follow fire road round to half way cafe. Third option is to reverse your out journey and pick up the escape road.
A slightly longer version but still within your time limit. From the car park ride up fire roads to get to Brutus and follow MBR round to pick up description from PH above.
It would be easier with GPX but I don’t use such technology. Get some route maps from MTB Wales site and it should make sense.