Dragon's Dogma: Dark Arisen

The Gazer is not any Evil Eye. You can find regular ones in locations such as the Rotunda of Dread, so don't get them confused. You'll know when you meet the Gazer because of it's massive size. It appears in the Shrine of Futile Truths in Bitterblack Isle.

Some basic tips for defeating it:
1. Bring Panacae or similar items. It will attempt to blind you, along with other afflictions. As far as physical damage, the Gazer relies on the tentacles like any other.
2. Attack the eye. It's the weakspot. Furthermore, the Gazer does not have a shield like normal Evil Eyes, so you can attack whenever and deal damage. Anywhere other than the eye, however, does very little. So don't waste the effort.
3. When you notice it's attention going to the tentacles (meaning it creates a magical sphere at the bottom of the shrine,) immediately hack them away. You can then use the cannon it created to fight back against it, dealing massive damage for a short moment.

The trophy will pop right after it's dead. The Gazer will respawn in both pre-Daimon and post-Daimon, so you can farm it whenever you'd like. I also recommend looting the area it's in, because there's quite a few chests. The materials the Gazer itself drops is also generally regarded as rare.