How to Get a Heavy Core
The heavy core is the rarest piece of the maceand there is exactly one place to find it: the ominous vaults of a trial chamber. No shortcuts, just ominous runs.
Ominous vaults, full stop. You make a vault ominous by clearing a trial under Bad Omen, then opening it with an ominous trial key. Normal vaults never drop it.
How often it actually drops
Roughly how often each reward turns up across ominous vaults. Relative, not exact, but it shows where the heavy core sits: at the bottom.
The loop you will repeat
What it is for

Quick answers
Is there more than one source for a heavy core?
No. Ominous vaults in a trial chamber are the only place it drops. A normal vault never gives one, so a run that is not ominous cannot produce a heavy core at all.
How do you make a vault ominous?
Clear the trial while under Bad Omen, then open the vault with an ominous trial key. Bad Omen comes from beating a raid captain or from drinking an ominous bottle before you enter.
What else do you need for the mace?
A breeze rod, which the Breezes in the same ominous spawners drop while you are clearing the waves, so one good ominous run can supply both halves of the mace.
Is the heavy core guaranteed from an ominous vault?
No. It is one of the rarer drops, so expect to open several ominous vaults across multiple trials before one appears.
Can I get it from a normal vault?
No. Ominous vaults only. A normal trial key will never give you a heavy core.
What is the heavy core used for?
One thing: crafting the mace, together with a breeze rod. It has no other use.
Where do breeze rods come from?
Breezes, which spawn from trial spawners (more often in ominous trials). Each Breeze can drop breeze rods.
Can I trade or duplicate heavy cores?
No villager trades them and there is no farm-able duplication. You earn them from ominous vaults.
First time down there? Read how to find a trial chamber and how to use trial keys. When you have your core and a rod, build the mace. Full drop tables live on the items database.
