I feel like there might be an issue where the volume of each individual elephant is so much greater than each individual fly that you won’t just be pachybombarding one BBEG, but the entire area, including where the players are standing.

For the “do the locusts consent?” question, I’m a fan of an oracle die.

I’ve been paying Cyberpunk RED recently, so I get the player to roll a d10 under their current LUCK stat. If they roll under, then they’re in luck and they get what they want.

For funsies, I’d say that succeeding indicates the locusts are a gestalt entity that is down for anything. In the context of the campaign, the party will encounter a gestalt locust swarm that wants something from the party.

Elephants are huge, not large. However, an entire swarm of horses would have a comparable effect.

A modern iteration on a classic. Word of advice, never eat a grape that you know was a hill giant two combat rounds ago.

I don’t really know d&d well, but I just looked up the spell and I think it says you can transform “any number of willing creatures”. So the DM could make an argument about whether insects had the intelligence to even qualify as being able to be “willing” for that.

On the other hand, I am a big fan of Operation Dumbo Drop Multistrike