Day 1
Poison modifier can be a bit rarer and only really spawns on Ruins, which tend to be a bit harder to do on day 1. We want to reach level 7-8 before we go towards any ruins, so for now, make your way towards a Church, clearing any Encampments, Forts, and Cathedrals.
Once we reach level 7-8, if we have time left, we can clear a Ruin with the poison modifier, or we can kill some Field Bosses if you find any, just be careful that it's not an Elite Field Boss since they will take quite long time before level 11-12.
It can also be very useful to move past the central castle to check if Trolls have spawned. If they did, we want to avoid this place on day 2.
If you cannot find a weapon we suggested, find one within the Greatsword Category if possible, otherwise Colossal Sword, Colossal Weapon, Curved Sword, or Hammer Category.
Day 2
On day 2, what we do depends on our findings from day 1. If there were no Trolls in the central castle, we could go there right away. Otherwise, wait until you are level 11-12 before going there.
Now for Shifting Earth events: If Noklateo or Crater spawned, you can go there immediately because they will give you enough runes for level 11-12 while also giving you the good reward at the end. Mountaintop can be done at the end of the day, and the Rot Forrest is great to do after the first shrinking of the Circle. Keep in mind that the Rot Forrest also has a ton of Elite Field Bosses, which will give a ton of runes and good rewards.
Speaking of, if you are done with your chosen route, clear Elite Field Bosses until the end of the day, since this is the best way to clear the gap until level 15.
If a Settlement is spawned, be sure to check it out to see if any good loot can be found there.
Day 3
Adel is very mobile for a dragon and will dash around the arena a ton during both his phases. Use your grappling hook to close the distance where needed, since it's a low cooldown anyway. The attack you need to be careful about is his grab, since it has a very big hitbox and it can instakill when you are below level 13.
For the rest of phase 1, he is pretty easy to deal with, especially if you have poison to stagger him constantly. He will still try to headslam constantly dealing AOE damage, but it's pretty easy to dodge during phase 1.
Once Adel reaches 50% HP, he will transition into phase 2. Be careful for his opener and run away as far as you can since he will erupt a giant lightning explosion around him after which he jumps into the air to divebomb into the ground, dealing massive AOE damage. He can repeat this attack during phase 2 if he feels like it.
During phase 2, his headslams are empowered to have a much bigger AOE. He can also now do 2 grabs in a row, which is trickier to deal with, especially if you are playing with a party, cause he can shift focus and dash to another person, grabbing them instantly.
Keep in mind that poison is less effective on him during phase 2 because he won't vomit anymore.