After flopping in European knockout fare without landing a punch, it took a flurry of blows from Andrew Trimble and Liam Williams to kickstart this semi-final and Ulster's safe passage into the final at the RDS in a fortnight.
After a nervous opening quarter, brimful of handling and kicking errors, Ulster settled into a familiar rhythm once Trimble had been sin-binned along with Williams, who reacted to the Irishman's reckless forearm smash with a thumping left hook.
In truth, Ulster should never have needed such a call to arms, such was the often feeble resistance of the visitors, whose attendance in the last four barely reflects well on the strength in depth of this league.
Tries from Lions winger Tommy Bowe and Robbie Diack gave Ulster a half-time lead before another from Tom Court just after half-time sealed the deal despite the briefest of rebellions from a pitiful Scarlets.
And so, as the multi-million pound Ravenhill facelift continues to take shape, so too the steady rebuilding of the side.
Mark Anscombe's men will be hoping that, when they return to the refurbished ground next term, they will do as Pro12 champions; having won in Dublin and seen off Glasgow already this season, they will fear neither of their prospective final opponents.
In a season where they could not avail of Stephen Ferris for a minute, were minus Bowe and Johann Muller for long stretches, as well as enduring the foibles of the international window, to finish top of the pile and then cruise into a final is no mean feat.
Scarlets' hopes of stemming a barren run in this ground that stretched back five years were hampered even before the kick-off, when Simon Easterby's gamble to include Rhys Priestland backfired when the out-half's troubled Achilles seized up in the warm-up.
Striking back from adversity has been an historic trait of Llanelli and they seemed undimmed in their early attempts to strike from anywhere.
It brought them immediate profit, Andy Fenby's blistering break, avoiding weak tackle attempts from Rory Best and Paddy Jackson, ultimately gained enough momentum for Dan Tuohy to concede a fourth minute lead for the away side through replacement out-half Owen Williams' boot.
Ulster responded immediately, with Diack's pinch allowing Ruan Pienaar to level matters.
Yet there was a tightness about Ulster's play, with some poor kicking from Trimble and a perfect pass from Darren Cave – unfortunately into the bread basket of his opposite number.
Owen Williams missed a penalty attempt as the home crowd shifted uneasily in their seats.
The game needed an explosion, and the powder keg emerged from the most unlikely of sources, with Trimble finding himself binned for a fairly uneven boxing match with Liam Williams.
Referee Alain Rolland decreed that Trimble acted first; if he did, then his efforts were risible for he departed with a remarkable shiner thanks to the retaliation of his opponents' more accurate and punishingly delivered haymaker.
All of this happened in Scarlets '22', into which Ulster had landed mainly thanks to an elegantly incisive gliding run from full-back Jared Payne.
His side wouldn't have to wait long and his searing intervention created the territory once more, Best rumbling well from a short line-out before Pienaar, defying the oohs and aahs of the crowd, dived left into traffic to find Bowe, operating on the left. We would soon know why.
Confronted by a fellow Lion, in George North, he may as well have been facing up to a corpulent tabby, such were the pathetic attempts of the Welshman to prevent the 26th-minute try, a simple step enough to secure Ulster's foothold in the game.
Once there, they stepped on Scarlets' throat. Pienaar missed a penalty but refused his next attempt, spiralling an audacious kick to the corner, from where captain Muller again called the line-out to himself. Ulster's maul did the rest; Scarlets' defensive maul just had a rest.
Diack bundled over and in nine minutes Ulster had accelerated from a nervy 3-3 to an 18-3 lead that, given the Welsh side's mood as they trundled into the sheds at the break, seemed virtually unassailable.
After the break, the momentum continued to be one way; only now Scarlets were abetting their own downfall by shooting themselves in the foot, or stepping on each other's.
Replacement Aled Thomas stepped on his captain Rob McCusker's toes as they dithered beneath a booming siege-gun punt from Pienaar and, as Ulster tore remorselessly towards the line, Cave did well with a forage before Court bundled over from a yard.
With that, the appropriately red-faced Scarlets, now also losing players to injury at a calamitous rate, folded their tents and dashed for their homeward flight, although at least Gareth Davies' fine individual try demonstrated that some fighting spirit resided within the away ranks.
Pienaar quelled the mini-riposte with a penalty for 28-10 before Sione Timani's trash-time try. Ulster's race is not yet run.
Ulster – J Payne, A Trimble (M Allen 76), D Cave, S Olding (P Nelson 67), T Bowe, P Jackson (P Marshall 60), R Pienaar; T Court (C Black 68), R Best (R Herring 73), D Fitzpatrick (R Lutton 56); J Muller, D Tuohy (I Henderson 67); R Diack, C Henry, N Williams (M McComish 69).
Scarlets – L Williams; G North, J Davies, S Williams (G Owen 21), A Fenby; L Williams (A Thomas 41), A Davies (G Davies 44); P John (R Jones 59), K Owens (E Phillips 47), S Lee; G Earle (J Ball 51), J Snyman; A Shingler (S Timani 45), R McCusker (capt), J Turnbull.
Ref– A Rolland (Ireland)