Shogetsu Form is used for your main burst. It will put you into the noto state for 20 seconds but still follows the normal noto rules.
The Noto skill itself only lasts for one use, it exits the state after one successful use of a Battou skill. So you want to use Shogetsu Form, Battou skill, Noto then another Battou skill.
Noto will also be used for your mini-burst after 60 seconds, since it only has a 60s CD instead of 120s like Shogetsu Form.
Make sure you're doing your dailies + Monster Park (even more so on reboot) as this is where Nexon puts the majority of the EXP.
The way the game has gone, grinding is something you do in your downtime. While you're doing something else, between quests or bossing, etc.
Nexon could make grind more exciting by bringing social/party play back into it but given how long it's been and Nexon's continued pushing of soloing everything even bossing, this is unlikely.
The game is sadly single player with multiplayer tacked on at this point.
Normal Guardian Angel Slime, Easy Lucid and Easy Will do not count for Special mission progress.
I have cleared these bosses multiple times and even slime once after the patch just to make sure, it did not count but did on the "boss" tab.
Edit: Clearing Chaos Guardian Angel Slime gave me the Normal Guardian Angel Slime progress.
Edit2: Clearing Hard Black Mage gave me the Easy Lucid clear.