There are two styles of essence in League of Legends crafting. Blue essence which is similar to IP for the older gamers, and is best used for crafting champions.
Orange essence is used for any pores and skin or aesthetic in the sport. If you have got a pores and skin shard or a ward shard, it'll require orange essence to craft. Similarly one can also disenchant their pores and skin shards and ward shards to craft orange essence, basically buying and selling one skin shard for every other, although the returns on disenchanting skins is very terrible.