You can unlock Greater Tempers in Diablo 4 through a new Season 16 system
Tyrael's Boons let you customize rewards, boost farming, and unlock new Greater recipes without owning Lord of Hatred.

War Plans are getting a lot of changes in Diablo 4 Season 16, but the new tactics tree is not the only addition.
Instead of seasonal powers, we get something pretty original for once. Blizzard is adding Tyreal's Boons. This is a new Season-themed War Plan tree that allows you to tailor your War Plan rewards and activities for that Season.
For example, you can find things like bonus Seasonal reputation or currency, or reduced Obols costs.
All Seasonal players can access Tyreal's Boons! You do NOT need to own Lord of Hatred for this War Plan Tree.
It Does Not Replace Seasonal Blessings
We compared it to seasonal powers, but a more appropriate comparison would be seasonal blessings. These used to change with each season, giving you bonuses such as more reputation experience or more gold and obols.
Tyreal's Boons sort of take a similar role.
Season Blessings will become a static system with the same five Blessings each season. So when you complete your seasonal journey, you still earn Smoldering Ashes, and you can spend them on your Blessings.
And on top of the Season Blessings, you will now have access to Tyreal's Boons, and this is what will allow you to get the other "blessings," basically.

Four Different Paths
Tyreal's Boon lets you pick between 4 different Paths. You can earn up to 132 points, and that is enough to allow you to spec into all four paths. Technically, you get enough points to pick almost all the nodes or max out the ones you really want.
These paths will most likely change each season. In Season 16, these are the four paths:
Curious Addition:
Modifies the Purveyor of Curiosities to increase chances for a second item
Offers either new item types or improves the chances for higher-quality items
You can also select an option to make the Purveyor far more expensive, but increase the likelihood of getting Ancestrals
Merchant of Mystery:
Adds a new merchant at Torment difficulty selling caches for
Forgotten SoulInvest points to increase the chances of Ancestral Caches
Select a path to buy caches with Runes or Gems, or increase the amount and quality of Ancestral Caches
Scent of Gold:
Increase the amount of gold and experience you get
One path also increases the number of Horadric Cube materials and Gem Fragments you find
The other improves monster drops of Gold and Gems
You can also increase your chances of finding a Legendary
Trash for Treasure:
Transmuting costs at the Alchemist are reduced
You can choose to invest in a better chance for
Forgotten Soul.The first path gives more
Obducite and
Scroll of RestorationThe other gives monsters a chance to drop more
Obducite and SalvageAt the end, salvaging Ancestral Items gives a chance to grant a
Scroll of RestorationIt also opens a new Horadric Cube recipe, Greater Temper, which upgrades the Tempered Affix on an item to a Greater Affix for the cost of 30
Scroll of Restoration and 1,000
Obducite
You can respec points whenever you want, but to unassign one point, you need to pay 5,000,000 gold. So it can quickly cost a lot if you are picking random points.
