Critters will distract the Grappler, so you can use it to avoid large units from being grabbed.
If Critters are not available, the best strategy would be to use smaller units such as Riflemen or Zookas. The loss of a single Rifleman or Zooka is usually immaterial.
The Grappler should be placed in the middle of a bunch of other defenses. As its use is best when grabbing a large unit such as a Tank, place it in range of multiple Cannons or Boom Cannons to eliminate them quickly.
You can also place it in the middle of a group of Flamethrowers to wipe out other units such as Riflemen or Grenadiers quickly.
At Mark 1, the Grappler has a black coil and a metal-like nipplers.
At Mark 2, the coil gains red amnd the nipplers becomes 3. It also goes red.
At Mark 3, the nipplers becomes 2 but gains a red material. The structure gains a reinforced platform.
Grabs an enemy unit and drags it next to the Grappler
Input total Statue bonuses to modify the statistics in the table below accordingly