I have a sprite token and hidden sprite call at a battlefield. It's the beginning of my turn. If I play the sprite call, do both sprites die since it's the beginning of turn?

No, your original sprite will die, but the new sprite summoned by Sprite Call will survive until the beginning of your next turn.

This interaction is possible because the Temporary keyword creates a triggered ability that goes onto the chain at the start of your turn, allowing you to react to it.

Sequence of Events

1. Beginning Phase: Your turn begins. The Temporary ability of your existing Sprite triggers and is placed on the chain as a pending item.
2. Reaction: Because an item (the Temporary trigger) is now on the chain, you may play your hidden Sprite Call as a reaction. It is placed on top of the chain.
3. Resolution (LIFO - Last-In, First-Out):
   • The Sprite Call resolves first: A new 3 [M] Sprite token with Temporary enters the battlefield.
   • The original Temporary trigger then resolves: The original Sprite token is killed.
4. Result: Since the new Sprite entered the battlefield after the Temporary trigger for the start of this turn had already been processed, it will not be checked for Temporary until the start of your next turn.

Important Clarifications:

• Rule Reference: Per Rule 336.1, the chain resolves in a Last-In, First-Out (LIFO) order, meaning the last item added to the chain is the first one to resolve.
• Hidden Restriction: Per RiftJudge FAQ #1553, because you are playing Sprite Call from a hidden state, you must summon the new Sprite token at the same battlefield where Sprite Call was hidden.
• Holding the Battlefield: As confirmed in RiftJudge FAQ #6560 and #6571, by reacting this way, you ensure you never lose control of the battlefield, allowing you to score a hold point if applicable.