Discard already suffers from doing nothing on an empty hand, the fact that Duress can still do little on a full hand means you have to be quite careful how you build with Duress and where
In Commander, you manifest dread three times per turn rotation
(1) Immediately after this effect resolves, Tribute Summon 1 monster, and if you do, it cannot be Tributed this turn
It also comes into play with a +1/+1 counter on it already, and since it has modular, you can move its counters to another artifact creature when it dies
It's an excellent source of card advantage in your manabase if you're playing at most one, maybe two colors, and it can fill in gaps for colors that don't have unmitigated access to card draw
All turned out first-rate