Yeah, that was sort of my thought. You can get around the intuition that this should be an action (like Hunter's Mark and Hex are) by tying it directly to another action: "When you take the Attack or Hide action, you can place a shroud on a creature you attacked or a creature you are hidden from."
Alternatively, have you considered making both Shadow Action and Shroud bonus actions and just expecting assassins to have to choose carefully what they're going to do this round, the way rogues do with Cunning Action and monks do with their ki abilities? There's some narrative appeal to that: an assassin is either plotting carefully or springing into action, but not both at the same time.
Yeah, I’ll keep that in mind as I playtest this version. It may end up feeling off, or it might work really well.
right now, the average level 2 turn is;
Bonus action place shrouds.
action attack, move, shadow action hide/gain “ignore difficult terrain and climb at speed”)
at 5th, that becomes
Bonus action place shrouds
Action attack, move, shadow action (as above, or intimidate a target)
Potential Reaction reduce damage, possibly spend Shroud to counterattack.
Okay, having written it out like that, I see potential issues more.
specifically, the bonus action is boring. Either it needs to not take action economy to place shrouds, or something else.
My issue with making the Shadow Action a bonus action is partly that it is then just Cunning Action but with different Cunning Action options. That’s much closer to “us this a rogue” than having expertise is, IMO.
So, I think I haven’t ever actually mentioned what the basic idea of shadow actions (and quick on the draw)
is. I basically wanted to make them special ways to Interact With An Object, which you can do as part of another action 1/turn, but situational in what actions they can be part of.
Perhaps I need to just make that explicitly what Shadow Action does, and tie Quick On The Draw, as well as the Specialized Tool benefits, to the Shadow Action.
And maybe, just to maintain narrative better, QoTD allows you to use a Shadow Action as a Reaction when you fail a relevant roll.
If I do that and make Shroud placement not need a bonus action, I could put Shadow Action as a bonus, and the round should work pretty well. Shrouds can’t be every round anyway, but it’s important IMO that assassins can gank their main target
and get away in the same round. Especially on a turn where they get their shrouds (and this damage potential) to its max. I don’t think it’s good design to require waiting more than 1 round to do the main thing the class does. So, attacking a mook and then regaining stealth in one round, while building shrouds, and then maxing the shroud in the next turn and ganking the prime target, is about the max tolerance for delaying
that core defining feature.
Might move the intimidation benefit of Inevitability of Death to a different level, as well. Level 5 is cluttered. Monk gets some stuff at ASI levels, and archetype levels, might do that, or push something further back.