The Angels took the lead slightly against the run of play seven minutes before the break when central defender Leon Legg powered in a header from John Westcott's corner.
Carl Rook doubled the advantage early in the second half - but the fightback began 10 minutes from time when substitute Tom Tsangarides beat Lee Worgan with a low shot.
The dramatic leveller came six minutes into added time when a free-kick caused mayhem in the Tonbridge box and the ball eventually fell to Nick Davis to turn home.
As a result of that draw and with Staines's game at Harrow Borough falling victim to the weather, Dover extended their lead at the top of the table to 20 points with a comfortable 2-0 win at Kent rivals Margate.
In front of a season's best crowd of 1,339 at Hartsdown Park, Andy Hessenthaler's side took a 20th-minute lead when Shaun Welford's header came back off the bar and keeper Pat Mullin before crossing the line.
It was 2-0 11 minutes before half-time when Welford scored his second with a shot on the turn.
The victory came at a cost for the Whites though, who saw Frannie Collin stretchered off with an ankle injury in the first half (that was after losing Jon Wallis to a hamstring injury suffered in the warm up) and then goalscorer Welford sent off in the closing stages.
Maidstone stay in fifth place despite a 1-0 defeat to Hastings at Bourne Park.
The only goal of a dull encounter came in the 65th minute when Antonio Gonella capitalised on a mistake by Ian Cox to score beyond keeper Steve Northwood, who came into the side after Andy Walker got injured in the warm up.
Meanwhile, Dartford's home clash with Harlow was called off.
Division 1 South
The clearest chances fell to Invicta. Youngster Kieron Byrne had the best of them in the 12th minute but his fine overhead kick from Darren Smith's free-kick was superbly tipped over by Matt Reed.
The Brickies - who are unbeaten in seven - had Reed to thank again after the break when he saved Jimmy Jackson's goal-bound effort.
Sittingbourne failed to seriously test Jack Delo, who was making his home debut in goal for Folkestone.
Jamie Kempster's 24th-minute header gave Cray Wanderers the lead at Merstham - but they failed to take all three points after the home side scored an equaliser four minutes into the second half.
Division 1 North