Important encounters and always facing resistance

Question

I chose to play as a pure fighter in a campaign. Went with warforged, opted play as a samurai, and started out as lvl 4.

I enjoy the campaign, and I feel like I'm fairly helpful in our random basic encounters, dealing a fair amount of damage. However, I feel completely ineffective when facing the more imposing enemies.

Our first end of dungeon boss was immune to non-magical attacks and his bodyguard resisted damge from non-silvered weapons. We slogged through the encounter, with my character only being able to do half damage the entire time. Then we had our next big confrontation at lvl 6, this time I've been able to silver edge my weapon but we are put up against a single vampire (five people in our party: Fighter/Rogue, Fighter, Barbarian, Sorcerer, Cleric). Again, I'm stuck only doing half damage, watching as the vampire recovers health every round and our party gradually succumbs to its charm ability. Eventually all of us are unable to fight and our session ended on a cliffhanger as to whether or not we just got party wiped.

If my character is going to be constantly running into creatures resistant to his attacks, what are some options he can take to be effective in combat without access to a magical weapon?

Answer 1

Not all hope is lost, there are several ways you can help your allies.

By dealing non-physical damage

Magic weapons aren't the only way to bypass physical resistance/immunity.
You can achieve this effect by:

• Asking your party spellcasters to cast a relevant spell (such as Dragon's Breath)
• Utilizing environment features (pushing enemies into fire etc.)
• Using consumable items (e.g. Alchemist's Fire)

By controlling a battlefield

Pushing, grappling, tripping - everything you can imagine. Unless you dumped your Strength ability score, it should not be a serious problem.

By helping your allies to land an attack

Using an action to help an ally will grant an advantage on their first attack, increasing effective DPR of your team as a whole.

By provoking enemies to attack you/absorbing damage

Essentially, by taking a tanky role, you will enable your teammates, if it isn't being effective, then I do not know what could be. Damage prevention is nearly equal to healing.

• Taking Magic Initiate and choosing Compelled Duel allows you to draw enemies' aggro just like in MMORPGs.
• Using a dodge action applies disadvantage to attacks against you and grants advantage on Dexterity saving throws.

Answer 2

Work more with the party

As you might know, 5e is designed in such a manner that players do not need magic weapons at all from levels 1-20. Some players may find this fun, others may not care for this at all.

A game I was in last year, we didn't have much in the way of magic weapon distribution at all until around level 8 or so. As a monk, when we fought shadow demons; we really fought shadow demons. They were incredibly dangerous for us. Upon gaining my 6th level class feature that made my fists magical, it marked a notable point in my character's adventuring career where shadow demons were not nearly as deadly as before.

So there are three options for you:

• The first is to seek out more creative avenues to attack in combat, either via the environment, grappling, aiding others, silvering your weapons, etc. Perhaps the best thing you can do is keeping Sneak Attack conditions in effect for the Rogue as much as possible. Taking the Dodge action reduces the likelihood of a hit landing on you, but your presence adjacent to the enemy means SA is still in play. Furthermore, if the enemy moves, they still trigger an OA from you.

• The second is to work more with your table to be more effective. If you can get access to the 2nd level Magic Weapon spell that will help (or the Cleric can do that now if they are Arcana, Forge, or War Domain). Later on, your cleric could cast the 5th level spell Holy Weapon (XGtE). Either would enable you to deal full damage with your attacks.

• The last option is to talk with the DM about how you're not feeling useful in combats. I would try the first 2 first, though, beforehand. It can be helpful to realize that not every combat is your chance to shine. Against an enemy with Magic Resistance, you will usually be able to more reliably deal damage to them than a caster and so casters will be better served by buffing you in lieu of casting damaging spells that require concentration.

Answer 3

Frame challenge; there seems to be an encounter design problem

Why is your DM putting you up against such creatures without giving you access to magical weapons?

I would be very annoyed at a DM who is effectively invalidating your build in such a way. There are ways around it using things like grappling to have some use, but it doesn't sound like you built a grappler.

Your next step is: Talk to your DM.

Maybe this is just an unlucky sequence of fights where you went somewhere he had planned for a higher level (A vampire is CR 13). Maybe he thinks it makes things interesting and doesn't realise you don't enjoy it?
Either way my suggestion is that you need to convince him to either drop that resistance, give you a magic weapon, or allow you to rebuild a character that doesn't rely on weapon attacks (If that is something you even want).