Handling surprize as GM

[Griogre]

Yes, base 10 + Dex mod + proficiency if applicable (what FG calls Stealth on the skill tab + 10). Generally in most of my games nobody but a scout type is being particularly stealthy. I'll have the scout roll once until the next encounter and use that roll but the rest all use passive stealth 10 + Stealth Skill. If they have disadvantage on stealth, ie heavy armor, subtract 5 from the passive stealth amount and if they have advantage on stealth, ie invisible add 5. This is all on pg 175 of the PH.

Using passive "rolls" speeds play in the same way passive perception and insight do. You can also use group stealth checks from 4E. You use these where the whole party is trying to do something where they can help each other out - you drop the DC a "level" (about 5) and see if the majority of the party passes the check - if so they succeed. I use that in scenarios where the whole party is trying to sneak into or out of a camp, ect.

I think a lot of people overlook the rule on dim light and where you have disadvantage on perception - this always applies to creatures using dark vision (who see as if in dim light). Thus its easier to surprise groups only using dark vision.