Playing in our weekly online game last night we had a new PC join us to replace a friend who sadly had to leave. The party already consisted of a Dragonborn Barbarian, an Arcane Trickster and me, a Div Wizard. The new PC happened to be a Firbolg Grave Cleric and my mind instantly popped with excitement at a mechanics interaction I hadn't realised before: I had rolled a 20 as one of my portents and that cleric has Path to the Grave!

The moment came where we were fighting a dungeon boss, the Grave Cleric used Path to the Grave. The rogue was next in initiative. I gave him my Nat20. The lvl7 Arcane Trickster wielding a Shadow Blade rolled 6, 6, 6, 6, 5, 5, 5, 4, 4, 3, 2, 1. After having only taken my Fire Bolt and a single great axe before this, the tiny rogue killed the boss with 111 psychic damage. Bonkers combo.

tl,dr; Path to the Grave and Portent are crazy good together.

I wouldn't say "crazy", really. It relies on quite a bit of setup and luck, especially if you want to avoid metagaming.

First you must roll at least one '20' on your divination roll which is only a ten percent chance per day, then the grave cleric, who must still have their channel divinity, must be before the rogue in turn order, the rogue must be set up for sneak attack and not have disadvantage. I'd say it was a good use of party abilities and call it a job very well done. :)

Quote from Lostwhilefishing >>

I wouldn't say "crazy", really. It relies on quite a bit of setup and luck, especially if you want to avoid metagaming.

First you must roll at least one '20' on your divination roll which is only a ten percent chance per day, then the grave cleric, who must still have their channel divinity, must be before the rogue in turn order, the rogue must be set up for sneak attack and not have disadvantage. I'd say it was a good use of party abilities and call it a job very well done. :)

 The beauty of it is that the Grave Cleric can ready their action to enact Path to the Grave also with a trigger of something like “at the top of rogues turn” for meta or “when the rogue is about to stab” for pure RP. 

We were very stoked that it just fell that way and this interaction just kind of evolved before our eyes before we knew what was happening. Not to say our cogs didn’t begin turning for future haha. The Rogue rolled real low for that hit too.   

This is not an interaction, it is simply the value of Path to The Grave, combined with a critical.  Your Div Wizard increased the chance of getting a crit, but that was it.

The rest was merely a combination of luck (getting the crit and rolling good damage), and standard optimal use of an ability (Path to The Grave on a high damage roll)

"tl,dr; Path to the Grave and Portent are crazy good together."

Here's the fix:

"tl,dr; Portent and (anything) are crazy good together"