Now I haven’t even attempted this achievement yet because I know that it’s going to be a long arduous fight, but my boyfriend, Millennium King , got the achievement and gave me this great tip.
Not all of the Striders are capable of destroying buildings. The few Striders that can are the ones that are closest to the ground, fast and whose upper bodies are well within reach. In order to get the achievement you need to focus on these little buggers and any Hunters that may be with them first. After they’re gone, you only need to deal with the tall Striders and their Hunters.
For visual help, check this clip out by YouTube user mactiddy:
aipha femaie (Still loading...) 
And, these low fast buggers tend to outpace their Hunter escorts. If you find the buildings they are targeting, you can wait for them at the buildings and take them out without any Hunter interference. Since they focus on destroying the buildings first, they won’t target you either, or your Magnussons. There are either three or four of them total. (It was indeed a long grueling fight and required a lot of restores!)