Control of Transcendence

Hello.

I've created yesterday a deck, that uses new opportunity, as it is a Narset Transcendent. I think, I made a quite nice U/W control deck, but I need a suggestions about sideboard. I'm thinking of another End Hostilities and Dissolve there, as well as Erase and Banishing Light. Although I have no idea, what should be in SB against Heroic. It is my nightmare, I cannot play against heroic, enough to say, that yesterday few times I have been defeated in 4th turn playing against mono W Heroic. Maybe I am missing something. All suggestions will be great - about SB and what possibly change in MB.

Thanks for your review and help.

(The deck in my profile is called Narset Control)

Cheers.