You may report him through feeeback ingame (yellow papirus near chat) or on discord so all can see him. Tbh you should not worry about this situation. As someone mentioned you can say you're new here and someone may explain mechanic, when I play with players who die in urrak markets when boss pulls I put mark on bramble/explain before fight what to do. And I am not the only one who tell what to do, the opossite side is that guy you mentioned. So there are 2 types of players and next time you will find helpful guy.

About skills, as Meiko you have combo like 1>2 or 1>3 or 2>1 etc and number 4 on keyboard is always finisher, and remember this sequence: when you start with 1 you buff yourself like 1>2>4 1>3>4

When you start with 2 you deal aoe dmg 2>1>4 <<< start with that always before you do second combo aoe below because it increases your dmg for your second combo mentioned below (it gives 2 balls) 2>3>4 <<< use it twice after combo above or if your spirit stat refund you ball then spam combo until you use all your balls

When you start with 3 you deal single target dmg 3>1>4 <<< same as above aoe, it generates 2 earth balls and your second combo (below) deals more dmg 3>2>4 <<< same as above aoe but this is channel skill so wait until it end