That is a good idea, there should be a way to block other users.

For example some people would find the following behaviour impolite or rude: Somebody asks a question. You take an hour of your time to write an answer. The same person askes the same question again, obviously doesn't even read the answers given to him.

There should be a way to block such users.

Eh, I see this a little differently. 

From the very start there was a metric ton of good advice sent your way, including instructional videos sent by@harleQuinn (from HellHades, no less) to help you get set up on the right path to get in a good spot in the game. I lost track of how many times she linked you those videos, to be honest. 

For whatever reasons you've been unable to apply that advice/knowledge - which is fine and can happen sometimes - but have followed that up by making rant titled posts often filled with rants as well. It has definitely come off as though you're unwilling to apply the often thought out and well written advice. 

You're not the only person on the forum and open yourself up to criticism with how you've acted at times. It especially comes off poorly when it seems as though you don't acknowledge any of the help people have sent your way, followed by making new threads covering the same topics. In fact, it comes off as though you're just outright ignoring. 

Yes, the game can be difficult - especially towards the beginning of it due to all the mechanics involved - but you have to take the time to help yourself, too. Especially when a large percentage of people replying to your threads tried to help you fix mistakes you were making. 

I am sorry you haven't had a good experience, but I do think you're frequently mixing up blunt, honest advice with being rude. Anwyay, best of luck and hope you get things sorted.

You are very sure people are being mean to you, including being very upset at one of the other moderators here who was defending you, and threatening to report him across multiple threads. All he was doing was telling others to chill out, and on your behalf, mind you.

Honestly, these folks are legitimately giving you their best advice, taking their own personal time to type out long responses with screenshots, searching up video links, and working to help you. None of us get paid to post here. We are all spending our own personal time to do help. But if you hear anything at at blunt, or if someone asks you if you have even had time to apply the advice we have given, you react very poorly to it, and create new threads to complain about the moderators, the posters here, and act as if giving you blunt advice is the same as insulting you.

Usually when people have you have been asking the same questions on the forums now for three weeks+, they ARE trolling us. Getting some sort of fun out of wasting out time and good advice.

The answer to almost every problem you have posted is as follows "Farm champs as food using the videos Quinn linked, and use those newly 60'd legendary champs to progress."

In answer to some specific issues you've brought up. 

1. Lyssandra is one of the best champions in the game for Arena, getting her faster, to over 280, is about farming 6-6 Campaign for Speed Boots and 6-7 Campaign for Speed Gear. After that, you'll need to farm Dragon.
2. Mixed gear is fine. Stats over sets. The only champs you care about sets on is 6 speed pieces for Lyssandra and potentially Lifesteal for Kael so he can farm 12-3 for food. 
3. Scyl and Thenasil's power are not very important. Champ power is mostly weighted for Crit Rate and Resistance, and therefore has little impact on whether or not a champ can actually perform in game. It is more important that you build them for the job they are going to do in your teams. Don't worry about power, only worry first about Speed, Accuracy and Survivability, for most champs.
4. Food farming is simple enough IF you watch the videos. If you cannot understand what the videos are explaining, please DM me and I will see what I can do for you.

I have suggested you message me several times for help, and you have not done so once. Opening new threads to claim what we suggest is impossible, or be angry at everyone here...well, it isn't really making use of our advice, nor personal offers to help you. When people offer to take their personal time to help you, and to help JUST YOU in private, better to utilize that help instead of saying "Done. Just rude players. I will figure it out eventually. Should be able to block players." 

Seems to this girl it is extremely rude to attack people offering help, but I am just the fool offering help, so what do I know?

I hope you figure it all out. Any other anger posts from you will be deleted, and you will be given more timeouts to reflect. Have a good day!