Tips to Endgame
Cannot attack and summon in the same turn, each is a separate action and they can only do one thing per turn. How to deal with them varies depending on your class. Range can pretty easily snipe them with an unaware critical hit, then move back out of sight and repeat. By using hit and run tactics you can avoid getting swarmed by vortexs. For melee it depends on where it is located, the unaware crit hit is usually still possible with some SP. Often, not engaging is the best choice if you are not equipped to take it out.
For vortex swarms
Range characters will have no issues – kite back and kill like any other slow melee. For melee, the best option is a spear as that prevents damage shield (best weapon in the game by far). If you didn’t get a spear, whittle them down with terrain and ranged damage if possible, otherwise use stairs to break the fight up into manageable chunks so you can regen.
For crystal golems as a ranger
Terrain works well (lava is great), as does knockback into a pit (plenty of sources of knockback in the game). If none is available consider if you have to engage – SP is great for avoiding annoying enemies. You can also lure them to the previous floor and ditch them. A strat that lets you kill all but 1 crystal golem is to use perfect aim and target a golem through the other golems (or enemy mobs). Wands and bombs also work great to eliminate a pesky golem.
Try the usual tactics to eliminate ranged enemies – hide around a corner and let them come to you. Again it depends a lot on your class, as a ranger you can easily pick them off with perfect aim 2. As a melee, retreating to stairs with a few sp and dropping the agro can be super useful.