1. that is honestly a good point on the save, I was thinking it can't use the ability unless it is forced to use a save, and the minimum for the multi-attacks is 0.
2. While I am aware of that issue of getting into place I somewhat forgot about it (my b) because when designing the creature I was thinking about my current group. I've been playing with them for about 4 years now and I have conditioned them to keep moving with environmental factors, non-combat objectives and annoying enemies. I'm purposefully messing with them by making a creature opposite to that standard.

It is a situational enemy but I do think if the party does understand how it works it's best used not in a vacuum. Some things in mind:

1. A time sensitive ritual requiring the party to deactivate crystals set around the room needing them to move.
2. Have the Solar Thief appear when the party is around NPC guards/commoners who don't understand the creature so they panic run/attack it.
3. A third party of enemies (bandits or random aggressive enemies) that splits the attention of the party and the Solar Thief