Steel Dragons,like Black Dragons,are high-defence,high-Hitpoint monsters that can be tedious to RuneScape gold kill. Their primary attacks include a strong dragonfire breath and powerful melee attacks,so you'll need to bring protection prayers like Protect from Melee and Piety to maximize your efficiency. Although the introduction of Project Rebalance has made Steel Dragons weak to Earth Spells,they remain a slow kill,and their loot table isn't very rewarding. Steel Dragons often come in small task sizes,and even with Earth Spells,these tasks can take far longer than preferred. Given their high difficulty and low reward,Steel Dragons are a prime candidate for blocking.
7. Mithril Dragons

Although Mithril Dragons are unlocked through Slayer tasks and offer good experience for higher-level players,their slow kills and low drop rates make them inefficient. They have a high defence level,making them challenging to kill without using powerful weapons and high-level prayers. Given their lack of good drops and high task weights,they don't fit well into an optimized Slayer strategy.
Conclusion

When you're grinding towards 99 Slayer,your primary focus should always be maximizing XP efficiency while keeping the grind as enjoyable as possible. While it's tempting to always aim for the most efficient tasks,don't forget to prioritize fun. Some tasks might not be as rewarding in terms of XP,but they can offer a break from buy OSRS GP the more intense grinding.