I don't like ayumilove, so I'd say no, it's not so good. :)

Ok Vladys, then some advice please :) I'm about to pick a mastery for Elhain.

My personal approach when I started the game was to watch videos on YouTube for the character that interests me, because in the videos the information is much more specific than any site. You can see the characters in actual gameplay. I can judge if this is how I use the character or what I look at in the video is not exactly what I'm looking for and then to decide to follow the guide or not.

This is the reason I wouldn't give you specific masteries for those characters you ask. You can use them differently than I do, and that won't help.

Your characters are quite used and you will surely find plenty of content for them. Personally, I like Kizzle's content, it usually goes into great details. Then we have Hell Hades, StewGaming, Chofly Mobile, Salt - each with their own approach to the champions and how they use and develop them. You can take something from them if you find it useful, until you start to develop your own aproatch..

*edit - also Elhain... Don't overinvest there. She is usefull early / mid game and where raw damage is needed or you still don't have any farmer, but it will be way too much to go full mastery for her. 

And paying 800 gems early to max one or two realy useful champs isn't bad idea too. 

Some of the Masteries Ayumilove recommends on her site are not great.

However, I looked on Ayumilove website.

I saw the below mastery for Elhain on Ayumilove website.

I think it is a pretty decent set up.

Arena - Campaign - Faction Wars

It looks like a pretty solid.