Lock the Eclipse light buff by becoming Invisible.
Use Cloak Arrow mode on quiver arrow (make sure Ivara is set as DEFAULT in control settings for tap/invert abilities).
Cast Cloak Arrow on a SENTINEL by running backwards, jumping and quickly aiming towards sentinel in a diagonal direction.
Eclipse light level is MESHLOCKED while invisible. Cloak while standing in light to lock light buff.
If you accidentally lock dark buff, roll to briefly exit the cloak bubble to gain light buff which will then be locked when you renter bubble.
Having too small a range will cause you to exit the bubble with the slightest movements as the Sentinel moves slower than you.
SHARDS:
2-3 Duration Shards
2-3 Energy Max Shards
.
Use this NEW and EASIER method to cast Cloak Arrow on sentinel:
https://www.youtube.com/watch?v=P-pTNCvRBBs&t=0s