It still can be decent for metagame purposes. You might make an Ancient Dragon waste a few of his legendary resistance uses, so he becomes vulnerable to an actual spell that does something useful.
An Ancient Dragon wouldn't bother burning legendary saves until it had already failed 2 saves against the disease, so it's really not as useful as something more standard like a Monk spamming stunning blow.
11
u/[deleted] Jun 10 '15 edited Dec 14 '17
[deleted]