Can a character with good/neutral alignment attune to a sentient magic item with evil alignment?
The greatsword Hazirawn in the Hoard of the Dragon Queen adventure is described as "A sentient (neutral evil) greatsword" and it requires attunement. Are there any restrictions on who can attune to it, or any rules explaining what might happen if a good character attempts to attune to it?
Best Answer
Attunement is not alignment restricted unless the specific item says it is (and this item does not say that)
There are no rules about who can attune to sentient magic items specifically, so the normal rules apply. If the item does not say that only a specific alignment can/can't attune to it, then any alignment can attune to it.
One example of this (as pointed out in Medix2's answer) is the Moonblade, which says:
Hazirawn has nothing in it that would suggest any kind of alignment limitation on it, so any alignment can attune to it.
When the user conflicts with the item, the item can make demands
Now, as far as what happens when a user with a conflicting alignment does attune to it, the rules for sentient magic items do go into some detail:
So, while not explicitly limited to alignment based conflicts, it seems entirely likely that a user weilding a weapon that is in opposition to their alignment would come into conflict with that weapon's special purpose (if it has one) at some point and the rules describe how to deal with it (up to and including the item taking control of the user).
The Hoard of the Dragon Queen does not note any particular goals or behaviors of Hazirawn, but a DM can (and likely would) come up with some things to make it interesting.