|Synthesize is the process used in game to upgrade resources, jewels and Upgrade Tomes to their next level. It is done at the Forge. This is the only way to get Jewels of level 5 and above (and in practical terms, of level 4 too, see Jewel Crafter).
To synthesize one needs a certain quantity of the base item (depends on the item) and 200 gold (500 for T3/4 items). It will produce one unit of the higher leveled item.
Also, to be able to synthesize the higher quality resources you need to have at least a tower or magic skill type at a required level:
Synthesizing is subject to a cooldown. The better items you create, the more the cooldown bar increases (or decreases). The maximum cooldown is 1 hour (VIP 8 will completely remove it).
This table provides some info as to how each resource increases the cooldown-timer.
|Tower / Magic resources
(T1: Earth Essence T2: Pure Earth Essence T3: Perfect Earth Essence T4: Magical Earth Essence)
|Tier 1||15 minutes|
|Tier 2||20 minutes|
|Tier 3||20 minutes|
|Crown Port resources
(T1: Black Iron Ore T2: Rich Iron Ore T3: Refined Iron Ore T4: Magic Iron Ore )
|Tier 1||10 minutes|
|Tier 2||10 minutes|
|Jewels||Tier 1||30 minutes|
|Tier 2||25 minutes|
|Tier 3||20 minutes|
|Tier 4||15 minutes|
|Tier 5||10 minutes|
|Tier 6||5 minutes|
|Rural Camp Resources
(T1: Common Shield T2: Excellent Shield T3: Pure Shield)
|Tier 1||5 minutes|
|Tier 2||5 minutes|
(T1: Madantium, Rock Block, Magic Hammer)
|Tier 1||30 minutes|
|Upgrade Tomes||All Tiers||5 minutes|
Synthesizing may be useful to reduce the number of resources you may lose in the Prison, since the only resources you may gain or lose there are the lower tiers.
Since each level different level of jewels and upgrade tomes occupy a separate slot in the inventory, it is useful to think strategically and not upgrading them at the first chance, but wait for a convenient moment when you are ready to use the new items immediately. See inventory for details.
Once you break into the 31+ levels, it may be useful to upgrade one of your tower types and one of your magic skills more that the rest, to reach level 41+ and maybe even level 51+ before the others. This may help you to deplete the higher-quality resources in different quantities, allowing you a greater strategic flexibility with respect of claiming the Level Taxes.