Aven Interrupter interaction with
Aven Interrupter interaction with Fierce Retribution
My opponent cast Aven Interrupter to exile my Fierce Retribution. Afterwards, I was unable to cast the spell for it's Cleave cost while it was plotted. Is this the intended interaction? I couldn't cast it during my main phases with either method of casting. This was during a Premier Limited OTJ Draft.
Thank you for your time and effort.

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Rezzahan#77802 commented
A plotted card can only be cast with sorcery timing. It also has a cost of "without paying its mana cost" which is an alternative cost. As is cleave. You can only apply one alternative cost to a spell, and due to plotting, it has to be the "free" one. Since you can only cast with sorcery timing, you can never cast a plotted Fierce Retribution, because there are no attacking creatures in the main phase, so you lack legal targets. Without a legal target, the spell cannot be cast.
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sparksfamilyvalues#95319 commented
Plot creates a condition upon when you can cast a spell - at sorcery speed, which is during your main phase with an empty stack.
Plot also allows you to cast the card from exile for free. This is an alternative casting cost, and you can't choose a different alternative casting cost like Cleave when casting a card that has been Plotted. If it was an additional cost, like Kicker, it would work.