Are these custom MTG cards balanced for Modern and Commander?

[SeekerOfTruth007]

Deceive Device U

Sorcery - Mythic

The next Artifact spell you cast may be cast without paying its mana cost.

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Sift U

Instant - Rare

Look at the top five cards of your Library. Put one of them into your hand, one back on top of your Library, one back on bottom of your Library, one into your Graveyard, and the last into Exile.

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Specter's Double UU

Creature - Shapeshifter - Rare

Vigilance. Menace.

Specter's Double may block an additional creature.

2/2

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Mouth of Sauron 3BR

Creature - Horror - Rare

Each opponent plays with the top card of their Library revealed. You may play cards revealed this way as though they were in your hand and without paying their mana cost. If you cast a spell this way, pay life equal to its mana value. You can't cast more than one spell this way each turn.

4/4

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[AI Opinion]

Fun designs 😄

Deceive Device is too strong. One blue mana to cheat out any artifact in Modern is broken, especially with things like Blightsteel or huge combo pieces. Needs a much higher cost, extra conditions, or to reduce cost instead of fully free.

Sift is actually fine and very cool. Instant, card-neutral, huge selection but no raw advantage. Easily printable at rare.

Specter’s Double is underpowered. Double blue for a 2/2 with vigilance, menace, and can block an extra creature is cute but below Modern power. You could safely make it a 2/3 or add a small upside like a triggered ability on blocking or dealing combat damage.

Mouth of Sauron is scary but probably too pushed in Commander. Letting you cast off opponents’ libraries for life is similar to Bolas’s Citadel style effects but on everyone. The limit of one spell per turn helps, but four mana for a 4/4 with that text might be too efficient. I’d either raise its mana cost, make it 3/3, or require you to pay full mana and just let you play from the top of their library without the life-cheat.

[Anonymous]

Huh?

[SeekerOfTruth007]

I'm querying the AI, since it usually understands what I'm talking about, but not always.

I'm obviously not interested in addressing myself to people who only want to talk about blow jobs and anal sex.