Lancashire 181 for 6 (Buttler 58, Croft 40) beat Worcestershire 177 for 9 (Santner 57, Hose 42, Mitchell 3-9) by four wickets
Opener Buttler posted only his second fifty in 14 T20 innings dating back to April when he was playing at the IPL, hitting five fours and three sixes.
They shared 59 inside six overs for the fourth wicket to advance from 65 for 3 in the ninth over after Colin de Grandhomme's seamers had openers Brett D'Oliveira and Michael Bracewell caught at mid-on and mid-off.
This was a curious innings in so many ways on a two-paced pitch. Santner offered two relatively straightforward catches to Mitchell and Rob Jones on seven and 10, allowing him the chance to take the lion's share of 28 off compatriot de Grandhomme in the 18th over. That included three sixes - one pulled off a no-ball above waist height.
Immediately either side of that over, Mitchell removed Kashif Ali, Ben Cox and Ed Pollock as the the score fell to 173 for 7 in the 19th, Cox and Pollock both falling to Croft catches. The first was a stunner diving away to his left at mid-off. But Mitchell only bowled two overs.
Santner reached a 30-ball fifty in that blitz against de Grandhomme, also ensuring his fellow all-rounder an unwanted place in the Lancashire record books with their most expensive spell of two for 57 off four overs.
In the early stages of Lancashire's chase, Buttler dragged Adam Finch over wide mid-on for four before, in the fourth over, scooping Pat Brown for six over fine-leg and easing him through midwicket for four next ball.
In moving to 19 and the Lightning score to 30 without loss after four overs, it already had a feeling of a return to some kind of form for the superstar opener following a run of five ducks in 13 T20 innings prior to this. And that is how it transpired.
At the end of fifth over, Buttler's opening partner Phil Salt chipped Dillon Pennington to mid-on before Luke Wells miscued Finch high to square-leg in the next as the score fell to 38 for two.
For the next few overs, Buttler and Croft struggled for momentum as the scored moved to 59 for two after 10 overs, 119 more required for the hosts.
Buttler then hit back-to-back sixes off Pat Brown in the next, with another scoop on his way to 50 off 37 balls.
Then 54 runs came off the next four overs before a hiccup. Buttler edged Pennington behind and Croft was run out following a mix-up with captain Liam Livingstone to make it 114 for 4 in the 15th over with 64 more required.
Mitchell then hit a straight six off Santner's left-arm spin to take the target to 31 off 3 overs at 147 for 4.
But Livingstone (23) drilled Brown to mid-off before the four-time England seamer had Tom Hartley brilliantly caught and bowled next ball. At 157 for 6, Lancashire needed 21 off 14 balls.
But that target was reduced to four in the last over, with Mitchell finishing it with a straight-driven boundary on the up.