Common enemy in the poisonous swamp area of Blighttown. A giant leech that's slow and typically found in groups.
Swamp area, near the giant roots leading to The Great Hollow.
Giants Leeches are the best enemies in the game to farm mid-tier titanite ores. One instance of Green Titanite drop nets you 5 shards that can be converted into 25 Titanite Shards by Kingseeker Frampt.
- To farm the leeches efficiently equip the Rusted Iron Ring (found when you return to the Undead Asylum) and (ideally) the Covetous Gold Serpent Ring with 10 Humanities. Symbol of Avarice is too risky because you will get poisoned while farming these leeches.
- Start at the second bonfire in Blightown near Quelaag's Domain and leave the bonfire to the left (opposite direction of the lair).
- Go to the opposite side of the swamp from the bonfire. Following the wall in the left direction you should find all the leeches (about 20).
- No need to cure the poison, just heal when you need to. You should have enough healing power for one run even with only 5 estus flask charges as long as you don't get damaged by the leeches.