Fury Sliver — ruling 1

If a creature loses double strike after assigning damage in the first strike combat damage step (due to Fury Sliver leaving the battlefield, for example), that creature won't assign damage in the normal combat damage step.

Fury Sliver — ruling 2

Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesn't provide any additional benefit.

Fury Sliver — ruling 3

If the creature type of a Sliver changes so it's no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures.

Fury Sliver : règles, fonctionnement et interactions (MTG)

Fury Sliver is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

All Sliver creatures have double strike.

How it works : Fury Sliver

Original English text — Wizards of the Coast / Scryfall

#1March 19, 2021· Wizards of the Coast
If a creature loses double strike after assigning damage in the first strike combat damage step (due to Fury Sliver leaving the battlefield, for example), that creature won't assign damage in the normal combat damage step.
No other card is named in this ruling.
#2July 1, 2013· Wizards of the Coast
Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesn't provide any additional benefit.
No other card is named in this ruling.
#3July 1, 2013· Wizards of the Coast
If the creature type of a Sliver changes so it's no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures.
No other card is named in this ruling.