The Energiser Gem is a held item that reduces the SP cost of skills by 1.
How to Obtain
- Claim from the milestone tab upon reaching Lv. 51.
- Gold chest in the southmost part of Ixqun.
- Use the Drill Shovel (S) / Drill Shovel (G) to dig it up in the fartest north of Hayville.
"Reduce the SP cost of your skills by 1 point."
Since the game is supposed to use the US English vocabulary, the term Revitaliser should have been translated as Revitalizer due to the differences in spelling between UK English and US English. Some rules and/or examples about spelling differences between the two can be found here.