Each puddle needs at least one player standing in it to stop adds from spawning, you can tell this is successful when the purple orbs around the puddle stop moving. Players need to keep an eye out for Water Rune, where Titania places four puddles of water in the room.
Anyone standing nearby to this can easily get killed. For starters, ensure that only the main tank stands in front of Titania as she will often use Divination Rune, which is a tankbuster move spread out in a cone towards whoever has hate. The first phase is the easiest, but there's still a number of things that players should watch out for.
