You will get the objective to ‘Clear the corruption in the Lantern Cave’ during ‘Taro’s Regret’ Mission in Forgotten Forest after Mage Boss Fight. This article shows how to clear the corruption in Lantern Cave.
Clear the corruption in the Lantern Cave
After the Mage boss fight, enter the cavern cave area through the big entrance at the location highlighted below.
After entering through the gate, turn left and climb up the mountain wall as shown below.
After climbing the wall turn right. You will find your path blocked by corruption. Destroy the blue bulb on the tree next to it to clear the corruption and move ahead.
Move ahead and turn right. You will find a teardrop on a puddle of water here. Shoot three blue crystals on the trees nearby. On crystal is right behind the tear. One on the left side and one on the right side. After you have shot the three crystals, a waterdrop will fall. Guide the waterdrop to the tear. This will make the plant grow. Summon tear from the plant and guide it to the right and clear the corruption as shown below.
Move ahead and you will reach another area with a teardrop. Shoot the blue crystal on the tree and a waterdrop will fall on the tear making plant grow from it. Summon the tear from the plant and use it to clear the corruption to clear the path.
Move ahead and turn left. You will see some more corruption blocking your path. Destroy the blue bulb to clear the corruption and unblock the path.
Go ahead in the unblocked path and jump down to reach the underground area. Slide down to the bottom. At the end of the path, you will find a switch on the floor. Stand on the switch and use pulse to open the door in front of you as shown below. Go inside and defeat the Shrine Guardian to complete the objective.