Can someone help me on HMS?

I'm still learning the attack patterns, myself, so I can't really help you there. (Though, I don't know how good Naveed is since he doesn't have 100% Stun Resist.)

What I do recommend is looking for groups on the DL Discord. As long as you can meet the minimum HP and gear checks, those people are more than happy to help! (At least.that's how I've been able to clear HMS--not deathless though.) Plus, there's always going to be active people on there.

I don't know if Gamepress has the link to that Discord, but you can find one on the Dragalia Lost subreddit.

Naveed is not a unit that you should use to beat HMS, he doesn't have stun res.
V!Hilde is good if you have a pro team with you, but can't cure stun. Verica is better because she's easier to use.
Use the 4* staff (MUB) to have one more heal, use Phoenix, and spam the auto attack.
If you're a Verica, you will be able to heal your teammates as soon as the first attack touch you.
When the boss is in overdrive, use two attacks then Force strike, and repeat.
Again, if you're a Verica, Don't be scared to use your S1 when two allies don't have much HP.
Keep your regen skill when you know that tattered sky is going to hit. Same for Storm Chaser.

If you have Naveed, I assume you have good equipment for him, so I recommend using a 5* Euden instead.

Just like Erhyon said, V!Hilde is best when you are very used to HMS's attack pattern, so a 5* Verica is best for beginners. Ark Voyager works great since it has a targeted heal, but since Verica already has two healing skills, you can also use the Endless Demise (5* Elemental Void Staff) for the much appreciated Skill Haste and Skill Prep, or the Staff of the Red Emperor (5* Elemental Staff) that provides higher stats and Recovery Potency increase skill.

For both of them, Phoenix is the best dragon and relatively easier to get and unbind, since you can also get Moonlight Stones from Void Battle exchanges.

Use shield right after the first move. Heal during the first trident tempest then regain skill 1 in time for the “I shall rend you asunder” move. This move is the MOST IMPORTANT part of the fight. If no one has been damaged by the wind balls, then you should heal just before the move where you all have to stay close hits. If someone HAS been damaged by the green balls, then heal just before the move where you have to stay close shows up.

The rest of the fight is really not up to you but your teammates instead. Heal them when they need it, and your job is done. But you should be wary of the next time the move where you have to stay close shows up. If you have your heal when this shows up, you can attemp to survive it. If you don’t, then I like to transform into Phoenix and save everyone that way. Another situation that could occur is that one of your teammates tank this move with their dragon, DO NOT go close to them if they are trying to do this. All of the above scenarios should allow your team to survive that phase of the fight. If you have enough DPS, then you should be able to win.

Do not play with Ezelith, Naveed, or anyone that doesn’t have stun res as you will not have enough DPS to finish the match.

Coming from a healer with over 20 clears.