Hello,
I've recently been running a lot of heroic Slaver's for the named and crafted gear, and wanted to share some observations about how mythic works on these items.
Slaver's gear is cool partly because there's two types of mythic bonuses: the standard named mythic drop and the crafted mythic boosters which drop as ingredients in any slaver's quest. However, it gets confusing when these start to work together.
Crafted slaver's gear (chains, shackles, rings) is relatively simple. They can't spawn with mythic drop boosts, but can be crafted with a +1 or +3 mythic boost.
Named slaver's gear is weird. They can spawn with mythic boosts ranging from +1 to +4 depending on the type of item. They can also be crafted on with mythic boost ingredients, with exceptions. If the named item fits in one of the slots that the crafted gear can go into (neck, belt, trinket, ring, feet, wrists), then they can have the crafted mythic boost on them. Otherwise, the UI will not even give you the option to mythic boost them.
This brings up questions about stacking. What happens if I craft mythic onto a named item that already has a mythic boost from a drop? Well, they stack. "Wait, this is DDO. You can't tell me they actually stack."
Haha, no of course not. I haven't tested every slot, but I checked a Symbol of the Slave Lords with both a drop and crafted mythic boost - it does stacks. On the contrary, a Ring of Power with both drop and crafted mythic did not stack. The wiki only seems to indicate that the Ring of Power doesn't have stacking mythic bonuses but I haven't confirmed with any other named items.
The whole crafting mythic system is a cool idea, but it need to be consistent. Why can we only craft mythic onto named items that share slots with the crafting items? It's a silly limitation. Is multiple mythic effects on the same item even intended? Why does it only work for some items? The idea of mythic is to have a rare and small but self-stacking boost in order to reward farming quests more and on higher difficulty - it seems wrong to have non-stacking mythic like we're seeing on Slaver's.
Anyways, hopefully this helps some people, and maybe we can get some developer comments on the thinking behind the crafted mythic boost stacking properties.