If your LRIG is Black, you must send 10 cards from the top of your deck to the trash, and if there are 5 or more BlackSIGNI in your trash, you must return exactly 5 Black SIGNI from your trash to your deck.
If you have 9 or less cards remaining, and this SIGNI's ability activates, you send all cards from your deck into your trash. You do not get to send 5 Black SIGNI back to the deck, since you did not send 10 cards to the trash from the deck in this way.
This will trigger a Refresh, ending this SIGNI's ability.
You must be able to send 5 BlackSIGNI back to your deck from your trash, otherwise you cannot send any Black SIGNI back to the deck.
If you send 10 cards from the top of your deck to the trash, and there are less than 5 BlackSIGNI in your trash after, you may not return any of them to your deck.
If you send exactly the remaining 10 cards of your deck to the trash, and there are 5 or more BlackSIGNI in your trash, you do not immediately refresh. The rest of this SIGNI's ability finishes, returning 5 Black SIGNI from your trash to your deck. Therefore, you will still have cards in your deck.
If you send exactly the remaining 10 cards of your deck to the trash, and there are 5 or more BlackSIGNI in your trash, and among the cards sent to the trash by this ability is Code Anti Texahammer:
Select and return 5 BlackSIGNI from your trash to your deck. Then shuffle your deck (which is only the 5 Black SIGNI).