I understand how bane focus work with other banes. But don’t get how it works with phantasm. If i roll a 5 extra over their defense I can make a phantasm for free?
There are a few Banes that don’t make a lot of sense with Bane Focus (such as Spying, and Truthfulness), and the general rule in Open Legend is that if it doesn’t make sense, then don’t do it. Phantasm is unusual in that it is a Bane without a target, and Bane Focus assumes that you have a target.
That being said, if you and your GM can agree on a way to make it work sensibly for your character then you can go ahead and use it. For example, maybe you could have the Phantasm only appear to the enemy you hit with 5+ damage, or the Phantasm must appear at the location of your target.
Don’t forget, Bane Focus gives Advantage 2 on Bane Attacks, which I would definitely count for invoking Phantasm.
I agree that for a Damaging Attack, it would be hard to justify any use for it, although as a GM you can allow it of course.
Pretty much what both of them said. You still get the advantage 2, which is the main reason for Bane Focus for some builds.
The damaging attack would have to be Influence based, though. And for some (perhaps most) GMs, they might not allow that in the first place, which means you don’t even get that as a possibility.
As a GM, I’m not sure I’d allow it to happen on a 5+ damaging attack b/c of the nature of it. All depends on the background of the character and the setting. It would also matter some to me as the GM if you were getting advantage on the Damaging attack from other sources, and if you were getting more than Advantage 2, I would require you to roll again for the effect of the Phantasm I think, just b/c of how powerful phantasm can be potentially.