Why is the white slot important on Level 416?

It is the release buffer that lets short red and yellow stacks interrupt the long dark waves without blocking the yellow 7 or red 14 gate.

What should be saved for the end?

Save one hole for the final yellow release, then use it for the last cyan/white fragments and the dark cap.

Colony Flow! level guide

hard 5 colors

Peel the dark-purple shell from a cyan creature while the yellow 7 and red 14 gates compete for the same limited holes.

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Work through dark 32, 37, 34 and 40 as their holes return.
Send yellow 5, red 8 and the second yellow 5 while the yellow 7 and red 14 gates are open.
Route dark 38 with cyan 34/30, then clear the short dark 2/7/4/11 cards.
Use white 16 and cyan 30 after the dark shell opens, leaving the white buffer free for the next refill.
Clear dark 8/5/28/35/39 from short to long as the ants complete their return trips.
Feed cyan 19/34 and white 34, then remove the dark side pieces around the creature's head and body.
Reserve one hole for the final yellow release while the board reduces to a cyan face and dark top cap.
Finish dark 4/21/29 and the last cyan/white 34 pieces, then wait for the board-clear animation.

Colors in this level:

Dark purple, Yellow, Red, Cyan, White

Filling every hole with dark 38/40 and cyan 34/30 leaves no lane for the short red or yellow release.
Tapping a new stack while the last dark or cyan ants are still returning can cover the final gate transition.

Keep the white spare slot open for the red and yellow interruptions.
Use short dark cards before taking another 30-plus dark stack.
Wait for the final cyan and dark ants to return before tapping the last visible card.

Board notes 5 details

Layout: A cyan-and-white creature with a yellow tuft and red mouth stripe sits under a dark-purple shell. The lower gates show yellow 7 and red 14; the queue starts with dark 32/37/34/40, a white spare slot, then yellow 5, red 8, dark 38 and yellow 5.
Goal: Drain both colored gates, remove the dark shell, and clear the final cyan face, white fragments and separate dark cap so the board reaches the clear animation.
Opening: Work through the exposed dark 32/37/34/40 row as holes return, then use yellow 5, red 8 and the second yellow 5 before committing to the long cyan and dark cards.
Danger Zone: Starting dark 38/40 and cyan 34/30 together fills the holes while the yellow 7 and red 14 releases are still active; keep one white buffer slot open and wait for ant returns.
Mechanics: A two-gate shell-peel board that refills short dark, cyan and white cards as the full purple field breaks down into a cyan creature and a final dark block.

Why is the white slot important on Level 416?
It is the release buffer that lets short red and yellow stacks interrupt the long dark waves without blocking the yellow 7 or red 14 gate.
What should be saved for the end?
Save one hole for the final yellow release, then use it for the last cyan/white fragments and the dark cap.