I am not entirely sure if it procs on every tick, not done systematic testing on that. Combat can be quite fast paced, and lots of mobs around and lots of spells going make it hard to be sure of it.
I'd hazard a guess that it does, based on how some effects like alchemical attunement, seem to proc on every tick, but you know DDO, it might as easily be that it doesn't proc on every tick just because...
Ref 2 epic strikes:
The Fatesinger epic strike is a pre-requisite to the AoE SLA spell 'Echoes of Discord' in T2, which is what I really want to have.
'Echoes of Discord is a fast spell, benefits from metamagics for free, so to me, seem worth the 2 points spent to get it.
Being sonic dmg, it's another option for casting, in between weapon swings, to trigger a Lightning Strike proc.
Just to clarify: I do not use the Fatesinger epic strike at all. I don't find it stronger than Energy Vortex, and even if it is, the fact that I would have to constantly keep clicking to cast it would make it less ideal to me, since there is already so much to click and do. I would still prefer one click that automatically dishes out dmg afterwards (every 3 seconds for 15 seconds) without the need to re-click it every few seconds.
The way I approach builds like this (and my Blight caster hybrid), that have lots of buttons to press is:
- select your 'core' options that you want to press first because they are the strongest and/or the one that suit your playstyle the most
- I personally avoid giving specific orders for rotations because that can be quite rigid/prescriptive, but just as an example, I tend to use Energy Vortex pretty early on, sort of a couple of seconds prior to entering combat, and depending on who I am fighting, and if there is dedicated CC in the group or not, I pick my other choices
- if you don't get to press everything because things are dead: well, they are dead, you win

they were not needed for that encounter, that's all
- if an encounter lasts long enough to require using these 'extra options', then that's why they are there, especially considering cooldown on the 'core' options in your rotation
- if you find yourself never using something you selected from an epic destiny or enhancement tree, then re-spec and try something else
All in all, I personally feel the worst scenarios are finding myself without anything to press because things are all on cooldown.
Hybrids, in the sense of doing both melee dmg and some spellcasting, can be tricky in terms of reaching a balance.
- too much melee and rarely casting spells: it might be worth using a pure melee build instead
- too much casting, and rarely finding time to swing your weapon: it might be worth using a pure caster build instead
Just quoting myself from my Blight caster hybrid forum thread, where I commented on this too, to save me time typing it again:
Hope these thoughts are somewhat helpful