necro keeps getting one shotted need advice please

Im on my first character and somewhat of a noob on arpgs, im at the endgame and if i am carfull i hang around at the back, but too foten im suddenly killed by soemthing and im not sure. This is is true for bosses aswell , if im im in a a small arena i have no chance.
Im using a minion build and i enjoy the use of summons, but if need to cahnge one i can get rid of its the flame golem. i have some gmes which i dont use but there levels are all 19 getting close to 20.
IM jsut looking for advice please as i am a noob, please be gentle ;)

You should change your gems abit and swap most of your items for better ones! Mainly focus on resistances and life if possible

Without seeing the passive tree it's hard to judge, but there is a very large issue with affixes on your gear.

Affixes on gear are the main power progression in the game, and it is the main way you'll get the three basic defense layers in the game:

Health
Resistances
Armour/ES/Dodge (though this one also comes from the type of gear)

As a general rule you'll want to have capped elemental resistances, which by default is 75% (if you press 'c' to open character screen and go to defenses you'll see how much you have). In addition you'll want a max health affix on each gear piece or, as it looks like you're scaling ES, both high flat and high % max energy shield roll (see your shield for example).

One additional important thing to understand is the tier of the affixes. If you press alt while viewing the items you'll see additional information about that. Your shield has "+11 max ES" and "21% increased ES", while good (high tier, which actually goes down in number so T1-T2) can be "+80 max ES" and "100% increased ES" (a bit more advanced, but if you want to check, I pulled the numbers from here: https://www.craftofexile.com/?b=7&ob=both&v=d&a=e&l=a&lg=13&bp=y&as=1&hb=0&bld={}&im={}&ggt=|&ccp={} ), so just getting the correct affixes is not enough, you should also search for high level ones.

For resistances, for a start you'll probably want at least 80% resistance on each piece of armor (so you can get it with two affixes if each gives ~40%, but with three affixes each giving ~30% is also ok as a start)

that's why the previous comment mentioned that you need to replace most of your gear. They either don't have the defensive affixes or only have low level ones

ty very much, i tried to upload my passive skill tree nut not sure how it works

Without the skilltree its very difficult to see the full picture, but based on the items and gems alone there is so much to improve...

First of all, your goal needs to be to get high life rolls on ALL of your gear. Swap out the chest for a 4link/2link rare as well, this base has so little effect on you and also no life.

Get your elemental resistances to at least 75/75/75, improve chaos resistance as well but dont prioritize it.

After that, you definately need to fix your gems. Right now u run nearly every minion, which wont get u far. Decide for one sort of minion which will be your maik source of damage. Then adjust the support gems accordingly. If you want to play summon raging spirit for example, u dont need minion life, as they dont die anyway. Go with unleash. If you go with zombies, add more dmg like multistrike or melee physical damage. Same goes for skeletons. Summon phantasm works best on absolution and should be removed as well. Drop one golem.

With all those new gem Sockets you need to get in some Quality of Life, starting with auras. Most of your auras also affect your minions so its essential to have some.

Here are some suggestions:
- determination: increases armour, reducing physical damage u receive from hits
- discipline: gives u more energy shield
- vitality: increases life regeneration
- purity of elements: increases your elemental resistances and makes ummune to elemental ailments (freeze, ignite, shock for example)
- tempest shield: gives u a higher chance to block spell damage

Aside from all that: poe is not a forgiving game, even as casters or minion players u just cant stay back and wait there as things will inevitably jump or attack you. First of all, u need to learn the movement of the bosses, and as a starting point try to always move between Actions as long as there are enemies on the screen. Moving well is one of the best defensive things you can do in PoE and standing still will get you killed.