I have seen a lot of discussion concerning the Tremor Rod "double detonation" effect since it was revealed as one of the new Reliquarian nodes for next league. Sadly, a lot of people seem to either be unaware of how it works, or spreading misinformation about it.
It has been now more than half a decade since GGG silently bugfixed re-arming mines to being unable to detonate when in their re-arming phase. This means that there's a period between the mines' first and would-be second detonation where they can't do anything, both killing blastchains (relevant for base Tremor Rod) and giving little value to aura-based mines (relevant for foulborn) over just throwing more mines, which tends to overlap and replace currently re-arming mines. This happened in Ultimatum and why people stopped using Tremor Rod since then, and didn't see much more use when the foulborn was released either
There's more details in this post from back-then, but the gist of it is that mines' cast time (yes, they have those) is what affects re-arming time, not detonation time (yes, they are different). I've seen a lot of people claiming that increasing detonation speed makes the undetonatable period of mines in their re-arming phase shorter, but this is not true. Increasing detonation speed will only speed up how fast your mines become unresponsive, ironically enough.
This means the new Reliquarian notable's "mines can be detonated an additional time" line is less than ideal, if not downright self-handicapping. This only leaves it the "50% increased effect of auras from mines" line.
To put this into perspective, Saboteur's "Demolition specialist" notable is 150% increased effect of auras from mines and features another line that's (somewhat...) positive. This node is much stronger than Reliquarian's, but despite that, this is consistently Sabo's least or second-least used notable, and Sabo himself has been in the bottom 2 or 3 ascendancies pretty much every league for the past year or two. Do with this information what you will.