![](https://cdn.statically.io/img/www.enworld.org/dnd_news.png)
I mean,
fireball for starters. Anything that has areas-of-effect would be relevant.
Sleep would become significantly more powerful--after all, you can have the two spells start on opposite ends and work toward the middle, with only a slim possibility of overlap on the last monster.
Storm sphere and
vitriolic sphere get a pretty major power boost too, since those are effectively summoned units, and would interact oddly (would you spend one bonus action to employ both spheres? That's clearly too powerful, but if you only employ one sphere, there's little point to the twinning.)
Wall of Force becomes effectively
forcecage two spell levels lower for anything that can't fly (notably, it would also be two levels lower
and area of effect.)
Confusion gets a pretty major boost, since limited area is one of its major drawbacks (10' radius may not be
tiny but it ain't
large either.)
Tidal wave seems to get a major boost too, for the same reason.
Not to mention scorching ray and eldritch blast would become absolutely ridiculous. The former is a 2nd level spell. Twinned, it would be doing (up to) 12d6 damage for the cost of 2 sorcery points. Eldritch blast is a cantrip, so it still costs 1 sp, but at max level you'd be getting a free +4d10 potential damage (or +4d10+20 if you're a Sorlock) solely for spending 1 SP. That's a lot. And, again, I say that as someone who thinks Sorcerer needs some love.
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