This is actually very easy. This achievement is for the Tides mode unlocked when you complete the game and NOT for the tides mode unlocked via Uplay.
There are 8 waves. The first 5 waves are simple, just make sure to let the big guys run into the wall before taking them on. Upgrading your wind power to level 4 is recommended. I had it level 4 by the end of the game so I could easily take out large groups quickly.
The last few waves are simple but all end with a large runner, make sure to use POWER attacks against it.
Last but not least is the titan, clear the area of other enemies first before concentrating on the titan. This just will save you any headaches.
This is also a great mode to level up your grid in :)