Allen edged the opening frame, but his quest for three consecutive titles was then rocked by a Murphy onslaught before the mid-session interval.
Breaks of 74 and 69 helped put the 2005 world champion 3-1 up and a half-century in the next put him on the verge of a 4-1 lead, but Allen rallied with a 66 clearance to pull one back at 3-2.
A Murphy 67 - his fourth 50+ break in as many frames - restored the two-frame cushion, but Allen stayed close as he shut out 'The Magician' in frame seven to make it 4-3.
Murphy then went ahead once more by edging frame eight on the colours, but once more Allen responded with the semi-final's only century break in the ninth.
Yet again, however, Murphy held his nerve as he clinched the match on the black in a hard-fought 10th frame to earn his place in Sunday's final. Selby defeated Marco Fu by the same scoreline earlier on Saturday to become the first man confirmed for the 2014 final.
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