Jomel Warrican and Rahkeem Cornwall shared nine wickets, as West Indies A stamped their authority on the final "Test", closing 291 runs ahead at the Sir Vivian Richards Stadium.
England Lions were left to rue a disastrous first session where seven wickets were lost, as Warrican shone again and took his tally to 25 wickets for the series.
Andy Flower's side responded to the hosts 236, with a paltry 102, and it could have been worse for the Lions, had Haseeb Hameed not scored a resolute and disciplined 58.
Spin continued to dominate proceedings in the final session, as Somerset spinners Dom Bess and Jack Leach shared four wickets between them, leaving West Indies A 157/4 at the end of Day Two.
Keaton Jennings got things moving after resuming Day Two on 9, and flicked Raymon Reifer through the leg-side for three. But not long after, the left-armer got his revenge pinning the Lions Captain LBW for 16 with a delivery that kept slightly low.
Hameed then got off the mark with an exquisite cover drive for four against the same bowler, and followed that with a six back over Cornwall's head in the following over.
Cornwall responded though, beating the outside edge of Gubbins' bat, and then trapped the same man LBW for 4, to leave the Lions 49/2.
From there, the spinners began to come out on top for the remainder of the day. Warrican trapped Clarke LBW for 0, and debutant Sam Northeast then joined Hameed at the crease.
Northeast struggled to get going, having only landed on the Island 48 hours earlier, and flicked Cornwall to Hamilton at short-leg to depart for three.
Wicket-keeper batsman, Alex Davies, was busy between the wickets and used his feet well, before Warrican slid one through the gate and bowled him for 8.
The left-arm spinner then trapped Hameed LBW for 48. The Lancastrian was the star of an otherwise disappointing Lions batting effort, and was the only player to find fluency against the spin barrage.
Leach then followed Hameed back to the pavilion first ball, after Cornwall took a diving catch at leg-slip off Warrican, and the Lions were all of a sudden 92/7.
Paul Coughlin showed brief resistance but went shortly after the Lunch break, to Cornwall, after an excellent Jermaine Blackwood catch at slip.
Richard Gleeson was then out as well moments later, hitting a catch back to Warrican, which helped him bring up yet another five-wicket haul.
It was that man again who finished the job, as Dom Bess charged down the wicket only to be stumped by Shane Dowrich. The left-arm spinner finished with 6 for 33 and the Lions faced a 134-run deficit.
John Campbell and Kieran Powell started the hosts second innings briskly, bringing up the 50 partnership in just the 11th over.
Coughlin was then hit for a huge six hit out of the ground by Powell, as West Indies A continued to go at a run rate of around five an over.
But Bess entered the fray with his probing off-spin and had Campbell caught by Jennings at slip for 22.
The 20-year-old continued to find turn and bounce and picked up his second wicket on debut, wrapping Powell on the pads for 28.
Leach then backed up his Somerset spin partner and got his first of the innings, having the dangerous Blackwood caught by Gubbins at short-leg for 10.
The lead though still stood at 209 for the hosts and Shamarh Brooks and Jahmah Hamilton began to build a useful platform.
They brought up the 50 run partnership off 71 balls, after Hamilton hit a searing cover drive for four off Gleeson.
But, it was Bess again who broke the partnership, trapping Brooks LBW for 37 to leave West Indies A 127/4 and with a lead of 261.
Dowrich and Hamilton continued to accumulate in the closing overs and pounced on any loose deliveries from a tiring Lions bowling attack.
They were largely untroubled and reached the Close on 157/4, leading by 291 runs and leaving the Lions an uphill battle to save this match. Hamilton will resume on 31, while Dowrich is 13* overnight.