The illusory duplicate allows the cleric to have advantage on the attacks against a creature if both the duplicate and the cleric are within 5ft from the target "as the duplicate distract the enemy"

now, a creature who relay on blindsight only (such a gelatinous cube) shouldn't see the illusions, will the cleric still get advantage?

same for creatures who have truesight, tremorsense, or thermal vision

Quote from Nyal_the_fox >>

The illusory duplicate allows the cleric to have advantage on the attacks against a creature if both the duplicate and the cleric are within 5ft from the target "as the duplicate distract the enemy"

now, a creature who relay on blindsight only (such a gelatinous cube) shouldn't see the illusions, will the cleric still get advantage?

same for creatures who have truesight, tremorsense, or thermal vision

You only have advantage on attacks against creatures that can see the illusion. A creature that can't see the illusion for any reason (including that they don't have normal vision at all) wouldn't count.

However, I think under RAW it would still provide advantage against a target that can tell that it's an illusion (e.g. via truesight) as long as it can see it.