Mindwhip Sliver

• WWizards of the Coast2013-04-15
  Official Ruling
  If you cast this as normal during your main phase, it will enter the battlefield and you’ll receive priority. If no abilities trigger because of this, you can activate its ability immediately, before any other player has a chance to remove it from the battlefield.
• WWizards of the Coast2013-04-15
  Official Ruling
  If you cast a Sliver as normal during your main phase, it will enter the battlefield and you’ll receive priority. If no abilities trigger because of this, you can activate its ability immediately, before any other player has a chance to remove it from the battlefield.
• WWizards of the Coast2013-07-01
  Official Ruling
  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.
• WWizards of the Coast2013-07-01
  Official Ruling
  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.

Rulings via Scryfall