Does maelstrom and mjolnir stack? How?

[Steve]

Item

[Yozh]

I saw a video on Maelstrom. I don't think it stacks exactly. But if you have two I think each grants a 25% chance of chain lightning. If either of them triggers, there is only one instance, but having two is a 25% chance -two times. Three, three times and so on. Someone else could probably explain this.

[The_Technomancer]

Only the chance stacks but with about 3 of them almost all of your attacks will have lightning. This can be useful on certain heroes would need to focus on attack speed over damage (Tiny as he already has the damage), have some other passive they need to proc (sniper or troll, imagine bashing or headshotting in rapid succession), and/or have another source that can use the lightning effects (Arc Warden since he can have up to 3 of him constantly creating lightning jumping from hero to hero in a fight).