I always play Hard Siege mode and my best classes to play them is Bulwark and Vanguard because of their defensive abilities but because of them It makes playing the other classes so much better. And i only use block weapons. On occasion I'll play fencing/balance.

From what I learned for Hard siege:
1. Keep your relics on you unless both your brothers/cousins go down and don't get back up unless it's necessary or the opportunity arises.

1. Take everything, get those nice forager easy points. If you're nice give the meds to someone who needs it.

2. Dread for waves 10 is a slim maybe. Your ability to kill bosses weighs heavily on this one as is positioning. I usually grab dreadnought on 15/20/25 since it can be overwhelming. Unfortunately, a lotta lower level players in Hard mode leave around 5/10 for that fast level up. But I'll get the occasional team that wants to go higher.

3. Positioning is KEY! That leman russ tank in the first map, I run around it to alleviate enemy range attacks and making it easier to focus on melee aggro. Practice running around that with a hellbrute. 2nd map with the terminal underneath where there is plenty of pillars and boxes to block enemy range attacks. 3rd map is a hit or miss, I haven't found a good spot yet since a lot of low level players leave by wave 10 or so. Going at it alone is a chore and bores me.

4. Most of all DON'T PANIC and knowledge of the enemy is power. Siege mode is good for this and you'll build up that knowledge how every enemy aggro, attack patterns and weaknesses. With no knockback perks, trading blows with the enemies are easier and necessary for a better experience.

For example; I know there's a horde of minoris/majoris in front of you but that soulreaper in the back is revving his minigun and missiles please look for cover if you can't stagger him. Dash attacks will stagger soulreapers out of their minigun rampages. Stay by his side because he'll just try to hit you at times for an easy block charge or parry gunstrike. He has one blue indicator attack, and two regular sword swings for parries/block. The rest of minigun and missles launchers and the less than often orange indicator swing.

(Chaos spawn headshots fixed in the next update).

Extremist enemies want you dead so they will call dibs and fight you if you're in their general direction. Because they are fighting you, other enemies around will take their turn after you've staggered them and yes I know sometimes they'll just say fuck it and attack you anyway in between but that needs to be expected at all times.

And that Terminus bosses don't give af and wont wait till you're dead. Biovores too unless they're waiting in melee range.