How much does locking a transmog slot cost?

The extra cost applies to every roll for as long as the lock stays on, not just the first one. Locking is how you keep a part you like fixed while the rest of the look changes. With nothing locked, every component rerolls each time, so you pay less per roll but can lose a good result on the next one.

You can lock at most two of the three slots at once. One slot always stays open to reroll. The doubled price only covers a single lock. The cost with two slots locked is not settled here, so check the price shown before you confirm a roll.

Radiant Dream Shadows are the premium currency. You buy them in store packs paid for with Lumin Crystals. Glimmering Driftshadow is the free counterpart. The Walking with Irisalis Legendary Journey event store sells it for two Irisalis Petals each, so a locked roll paid in Driftshadow means grinding more event currency instead of spending money.

Not settled: The cost of a roll with two slots locked is not settled, and neither is whether rolls paid with Glimmering Driftshadow double under a lock the same way.