Your best late game strategy?

[incognito]

Still fairly new to the game and trying to figure out the ways in which the late games changes. I read in several Posts that many units, good in early expansion become far less useful in games with experienced players. ie archers/crossbowmen, infantries, etc. I also hear tidbits about end-game spell combinations that are hard to defend. What are some of the late game strategies that make this possible?

Personally, its hard for me to get past mass protected infantry with fire arrow archers in the background, but I gather this has an effective counter with high enough research, that makes it moot...