Galaxy, Dynamo through to MLS Cup
Alvaro Saborio equalised three minutes later, taking advantage of slack marking following a corner to head home from close range. However, the home lead was restored when David Beckham whipped in a trademark cross from the right and Magee powered home a header from six yards.
And 10 minutes later Robbie Keane, who had earlier hit the post with a low shot, took a pass from Donovan and scored with a low shot into the far corner from 10 yards out. The visitors had their chances after the break, with Fabian Espindola striking the bar and wasting a chance to set up an exciting finish when he shot wide in the 90th minute.
Beckham also praised Republic of Ireland international Keane as he said: "He knows how to score, he's done it his whole career. He scores at vital times and today he eased the pressure on us and got us over the line. We had a lot of other chances we should have put away but we're happy... it was always going to be a difficult game."
Asked how significant an MLS Cup success would be in his career, the former England midfielder said: "After my family it's the number one priority. Professionally I want to be successful and whether it's winning the Champions League, the Premier League or the Primera Division - picking up silverware means the same thing."
Andre Hainault gave the Dynamo a 53rd-minute lead when he tapped in from close range after substitute Jermaine Taylor had headed Adam Moffat's kick on to him.
The win was rounded off three minutes from time as the home side pushed forward seeking an equaliser, Carlo Costly outwitting defender Aurelien Collin before beating goalkeeper Jimmy Nielsen from the edge of the penalty area.