Fevered Suspicion — ruling 1

You cast the cards exiled with Fevered Suspicion as it is resolving. If you choose not to cast them, you cannot cast them later.

Fevered Suspicion — ruling 2

You may cast the exiled cards in any order, not just the order they were exiled.

Fevered Suspicion — ruling 3

If you cast a spell “without paying its mana cost,” you can't choose to cast it for any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, you must pay those to cast the spell.

Fevered Suspicion — ruling 4

If the card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

Fevered Suspicion — ruling 5

Cards you don't cast this way, including any exiled land cards, will remain in exile indefinitely.

Fevered Suspicion : règles, fonctionnement et interactions (MTG)

Fevered Suspicion 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

Each opponent exiles cards from the top of their library until they exile a nonland card. You may cast any number of spells from among those nonland cards without paying their mana costs. Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

How it works : Fevered Suspicion

Original English text — Wizards of the Coast / Scryfall

#1July 23, 2021· Wizards of the Coast
You cast the cards exiled with Fevered Suspicion as it is resolving. If you choose not to cast them, you cannot cast them later.
No other card is named in this ruling.
#2July 23, 2021· Wizards of the Coast
You may cast the exiled cards in any order, not just the order they were exiled.
No other card is named in this ruling.
#3July 23, 2021· Wizards of the Coast
If you cast a spell “without paying its mana cost,” you can't choose to cast it for any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, you must pay those to cast the spell.
No other card is named in this ruling.
#4July 23, 2021· Wizards of the Coast
If the card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
No other card is named in this ruling.
#5July 23, 2021· Wizards of the Coast
Cards you don't cast this way, including any exiled land cards, will remain in exile indefinitely.
No other card is named in this ruling.