D&D 5E (2014) Good 1st/2nd level spell to combine with Portent?

[FrogReaver]

Suggestion if you get a low roll

This is a reallly good suggestion!

 

[Horwath]

if it's 20, then Chromatic orb, might then be worth upcasting to 2nd level if target has vulnerability(that is then 8d8 damage, 16d8 damage with vulnerability)

 

[Horwath]

Suggestion if you get a low roll

yes.

Melf's Acid Arrow if you get a high one.

melf 's AA is horrible spell, even with crit is bad, might be circumstantially OK if target is caster with Conc spell active to force 2nd save in next round.