Illingworth will play holders Brighouse Rangers in the final of the Joseph Fee Memorial Halifax Cup for the second year running after winning 18-12 away to Stainland Stags on Saturday.
Driving rain meant the game was never going to be a classic and the result was in the balance to the end.
Playing down the slope, the visitors spurned their first chance when Adam Millns’ pass failed to find the supporting Luke Sutcliffe on the outside with the line beckoning.
Mills made amends on 13 minutes, breaking from his own half and feeding Lain Manning, who raced in from 20 metres out. Kieran Nicholson converted.
Sutcliffe added a second for Illingworth 10 minutes later after the defence failed to deal with Graham Dobson’s kick, the full back getting to the loose ball first.
Five minutes before the break it was 14-0, the best passing move of half paving the way for Brett Steele to send in Millns at the corner.
Stags hit back moments later with their first foray into the opposition quarter, crashing over from close range for a converted try.
Stainland then used the slope to their advantage to test the resolve of the opposition defence.
On 54 minutes they were rewarded for their efforts, going in under the posts from dummy half. The conversion made it a two point game.
The hosts missed a penalty but the visitors sealed victory six minutes from time. Following a ball steal from captain Andrew McElroy, Ash Ainley forced his way over wide on the right.