If a player-used projectile is destroyed by a field or reflected, any chain skills that the projectile skill transformed into will remain, replacing it, until they’re used.
Simplest examples:
main one: Guardian – Orb of Wrath: If the projectile is reflected/destroyed as described above, the skill will be stuck at the Detonate Orb of Wrath chain. Until that’s used (or the player switches maps/relogs), which is going to put the skill on a lot longer CD, the player is not going to be able to use Orb of Wrath again.
Thief – Cluster Bomb: Just as a above, the skill’s going to stay at the Detonate Cluster Bomb state until that’s used.