I’m always shocked to see these kinds of threads. Wyll is great! It’s no use looking at the pieces individually, he needs to be evaluated in the aggregate.
First, no one’s mentioned the imp yet, and that’s a crime. It’s an invisible flier that attacks for 1d4+1d6 poison. It’s also resistant to a bunch of damage types, making it surprisingly tanky. (I can’t find the exact stats, but they’re pretty good). The invisibilty means that the tough, angry thing appears at the best possible place as soon as your PC’s first turn; the flying means it will always be in the best possible place throughout combat. Final perk: Hexing the imp lets Wyll store a spell slot before SR.
Second, Hex ain’t getting the love it deserves either. It’s not just a combo with Blast, it’s fearsome with Scorching Ray. With high ground and Bless, you’re looking at the very real possibility of 9d6 damage. No need to worry about concentration when anything you target turns to ashes. And it just costs a bonus action!
Third, Blast may seem underwhelming, but when other casters are out of spell slots, their options aren’t better. Besides, along with Hex and the imp, Wyll has a base damage output of 1d4+2d6+1d10+cha. This assumes taking the Agonizing Blast invocation, which is a must have in my book.
Last, Wyll can cast neat spells. He’s not the only one, but I like having as many PCs as possible have access to Misty Step. Darkness may be bugged, I haven’t tried it. (I cast Fog once and I was so confused that I gave up on cloud effects).
Wyll’s a package, with high damage floor and ceiling throughout the day. (The OP clearly stated it didn’t matter to him, but I like to stretch in game days so replenishing spell slots with SR is relevant to me.) And I didn’t even mention Repelling Blast. Shove may be a bonus action, but it doesn’t have a range of 60 feet. I stopped taking that invocation because it straight up makes the game too easy.
