Sacred Flame is basically a freebie orison for your cleric to cast at range. It isn't that potent, but there are times you can get a 100% on using it. Not much damage and it has a save component. I know it is highly effective against the Undead - but don't quote me on if that is exactly true or what it is supposed to do. I don't know anything about 5E rules except what I skimmed about the changes on the basics. My experience with it though is that if you have a prone enemy or advantage it can increase from 50 or 45 % to usually 65% to 100% on a prone enemy. I mainly just use it when I'm out of spells or trying to conserve Shadowhearts spell pool for tougher fights. When it hits, it can do some serious damage, but that is when it hits. Since Shadowheart has a negative to her range ability I pretty much just use this for her until she closes to use melee. It is useful though. The fights just aren't very cleric friendly at the moment. Not many undead and so forth. That is where I think this spell gets more oomph! Oh and it seems to do well against planar enemies like devils/demons. At least when I used it that is on my cleric play through. It is best to use on low hit point enemies or when you are trying to close the gap, but don't want to burn all your actions on dash.