The XP from these demons doesn't make the grind worth it,and if you're trying to maximize efficiency,these tasks should be blocked as well. For Ironman players,these demons might be useful for RuneScape gold the Slayer Helm and other specific items,but even so,the slow kill rates make them better left off your task list.
Spiritual Creatures

Spiritual Creatures found in the God Wars Dungeon (GWD) are some of the most frustrating Slayer tasks in the game. These monsters don't have a particularly high task weight,but they are extremely tedious to kill. They drop poor loot,and getting to the GWD in the first place is a hassle. 

Without wearing specific God Wars Dungeon gear,you'll be constantly attacked by other monsters,which is an added annoyance. The task is already time-consuming,and the rewards just don't justify the effort. Unless you're specifically hunting for Dragon Boots or want to test your patience,this is a task that should remain blocked.
Steel Dragons

 Steel Dragons are notorious for their difficulty and slow kill time. Like Black Dragons,they have a strong dragonfire attack,meaning you'll need either an anti-dragonfire shield or an antifire potion,along with Protect from Melee prayers to mitigate their damage. While they can be killed with Earth Spells after the Project Rebalance update,it doesn't significantly speed up the process. 

The task request is usually small,but Steel Dragons hit hard and are tanky,so even though they don't take long to kill individually,they become a chore over time. Their drop table is subpar,and with their high defense stats,you'll find yourself getting very little XP from this task. Therefore,Steel Dragons are best placed on the Block List.
Mithril Dragons

Mithril Dragons are an optional Slayer task,but just like Steel Dragons,they are slow to kill and have terrible loot. They require the use of specific anti-dragon protection and are a pain to fight. Their slow kill speed and weak drop table make them a task you'll want to block. Don't bother unlocking them from your Slayer Master unless you enjoy wasting time.

In conclusion,Slayer can be a rewarding and enjoyable skill to train,but it's important to make the process as efficient as possible. By blocking these time-consuming,low-reward tasks,you'll increase your XP per hour and get closer to that 99 Slayer goal. Remember that,above all,you should prioritize fun,as burnout is a real risk in a long-term grind like this. If you've reached 99 Slayer,then you already know the dedication it takes—and with the right Block List strategy,you'll get there faster and with cheap RS gold fewer headaches along the way.