First of all, something I would recommend every solo player is to consider whether they prefer the solo mode or multiplayer mode with two randoms.

In case someone does not know how to start the solo mode:

From the Expedition screen go over to the matchmaking settings and scroll down to expedition type. There you can select single player (you should also be able to select duo mode or the normal trio mode).

If you play solo with randoms, I recommend you use the ping system, and it is strongly recommended to stay together. It is unbelievable how often I saw someone walk alone to the other side of the map and continuously dying and losing their runes.

Now let's come to some general tips.

1. Plan your route early.
At the start of the expedition, open the map and mark important locations — especially the ruin with the right element or status effect you need, the mine for the upgrade stone, and the final boss. As a solo player, it's very helpful to plan a good path so you don’t waste too much time or get stuck in unnecessary fights.

2. Time and resource management is very important.
You are on a timer, and as a solo player every death costs you time and runes. Avoid fighting every elite enemy if you don’t need their drops. Focus on fast looting, upgrading your weapon, and saving flasks for the boss fight.

3. Go to the church early.
The church gives you more flasks, and this is extremely important when playing solo. Without teammates to revive you or share the fighting, you need all the healing you can get. Make sure to pick up every flask upgrade you find.

4. Know your class stats.
Each class in Night Reign has different stats, and checking them before building your loadout is very important. For example, the Duchess has Dex (B), Int (A), and Fth (B), which makes her a good choice for hybrid caster builds.
I would recommend using a combination of a dagger with bleed or frost and a staff. If you don’t find a decent staff, you can also use a seal. A good spell I would recommend is Carian Slicer, which is very strong in close range.

As a bonus tip, spam her ability it has a short cooldown of around 10 seconds and reapplies the damage you've dealt in the last 3 seconds, which can massively increase your DPS if you time it right, especially during burst phases or stagger windows.

5. Check the boss weakness before starting.
Always look at the target of your expedition and see what they are weak to. For example, Adel, Baron of Night is weak to poison, and I would recommend using poison especially against him, since he gets staggered when poisoned.
Because RNG can be a bit annoying, I suggest looking at the map and checking which ruin has the symbol of the element or status effect you need that ruin will drop a weapon with the right effect.

6. Go to the mine at the end of the first day.
There you can get an Upgrade Stone 2 from a pumpkin head or troll and upgrade your weapon to epic quality. If you already have an epic weapon, you can skip this.

7. Be careful with the lava area.
In my experience, going into the lava area is often a bad idea when you play solo especially if you don’t have a lot of time left or a strong build. It’s harder to escape from than other zones, and the lava makes every fight more difficult.