Edited 04-Apr-2025 to reflect changes to Presence in patch 0.2.0 - nerfed from 6 meters to 4 meters.
Coming in patch 0.2.0, The Deepest Tower has adequate but not amazing 'basic stats' - life, chaos resistance and the like.
But it's one key line on the item that is the reason you'll use it.
"Enemies In Your Presence Count As Being On Low Life". "In Your Presence" defaults to a radius of four meters. (This is a good chunk of a screen).
Not useful on its own, this has very strong synergy with several passive tree nodes in the south of the tree as well as with the support gem Execute.
Reminder: This item applies only to hit damage. Sorry, damage over time enjoyers. Find another helmet to use.