just wondering if slivers in play affect slivers in your hand, i know theres ones that give flash or make them uncounterable but if i have like muscle sliver, winged sliver and manaweft sliver in play do the ones in my hand have those abilities aswell or not untill they enter the stack?
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Muscle Sliver says "All Sliver creatures get +1/+1." A creature only exists on the battlefield; in other zones (library, hand, graveyard), it is a creature card, not a creature, so this only applies to Slivers on the battlefield. In order to apply to cards not on the battlefield, it would have to specify with the word card - see Homing Sliver, which says "Each Sliver card in each player's hand has slivercycling 3."
Likewise, on the stack, it would be a creature spell. Root Sliver says "Sliver spells can't be countered." The First Sliver says "Sliver spells you cast have cascade."
Notice the difference in the wording of Quick Sliver: "Any player may cast Sliver spells as though they had flash." This grants the ability to the players, not the cards.
Some slivers say "All Slivers have..." rather than "All Sliver creatures have..." - see Necrotic Sliver. This can also only affect permanents on the battlefield because, again, it would have to refer to a card in a different zone.