Syrcus Tower has, outside of Castrum Meridianum and Praetorium, been the ARR dungeon that has suffered the most from item level power creep. The bosses here have mechanics, and those mechanics can be done, but the penalty for missing those mechanics is generally very light, with one or two exceptions that I will note.
The first boss, Scylla, generates AOEs with the staves that she spawns, you could kill the staves, but their AOEs are all telegraphed, and are easily ignored if you aren't standing in the bad areas, like donut-shaped damage fields, or linear attacks. She will tether random players with elemental balls, each of which needs to be handled in different ways. Lightning tethers need to be taken to the three pillars on the outside of the arena, or they will detonate and damage the entire alliance. Ice balls will unavoidably freeze your character in place, as you will see in the video. Players that get the fire tether need to draw the ball into a frozen character, for two benefits: first, it will end the frozen status on the ice victim early, and spawn a puddle of water, which will dampen the damage from Scylla's raid-wide Ancient Flare attack.
The second boss is Glasya Labolas. Never once in my FFXIV career ever seen this fight be anything more than a DPS race that ends before his actual mechanics can start. Just don't step near the Clockwork Square enemies, or you'll be trapped in them.
The third boss is Amon, Xande's chief scientist, and he's got quite a lot going on, including a redux of the King Behemoth boss from the Labyrinth of the Ancients. First, his Experiments will crawl toward him. If any of them reach Amon, then they will explode and cause status effects on the entire alliance, either Pacification or Silence, which will completely neutralize a physical fighter or magic user, respectively. Next, he will spawn strong monsters called Kum Kums. At the same time, he'll pull a similar trick to Scylla and tether players with a purple ball. If this ball hits the player, then they will be affected with the Mini status effect, and their combat parameters will tank severely. If you get a purple tether, drag it so it'll collide with the Kum Kums or the snake adds that appear later, and they will shrink instead, making them easy pickings. Sometimes, Amon will polymorph players into flame toads, locking off all their abilities except for a fire breath skill, which they can use to thaw players that will be frozen solid. Eventually, Amon will freeze three players and begin to cast Curtain Call, his ultimate attack. Everyone else needs to hide behind one of the frozen players to survive the lethal damage from Curtain Call.
The final boss is Xande, and he has a few mean tricks up his sleeve, but can be avoided or mitigated if you know what you're looking for. First are the yellow circles that cast Aetherochemical Explosion. Every circle needs to have a player standing in it when it detonates, or it will damage everyone in the battle. Periodically, at certain damage thresholds, Xande will leave the battle and call several meteors to fall from the sky, multiple small ones, and one very large one. You need only burn these adds down to prevent the party from wiping. When he comes back from these, he'll target three players with some scary-looking circle AOEs. This is actually damage-split field, and will damage for about 10k damage, split evenly among everyone standing in a field. Just don't stand in two fields at once, and you'll be fine. These will also spawn levitation fields to negate the follow-up Ancient Quaga, which will likely kill anyone on the ground that isn't at full health.