Elden Ring: Shadow of the Erdtree's early boss, The Divine Beast Dancing Lion, definitely gave me some trouble my first time fighting him. Thankfully there are some fairly consistent strategies you can use to make short work of the ancient being—just be sure to play more cautiously once he reaches phase two.

Divine Beast Dancing Lion Phase One

I've found Divine Beast Dancing Lion's first phase will last anywhere from one third to half of his health bar being depleted, and this is the safest time to play a little recklessly and tack on damage. I found that during phase one, Dancing Lion is very susceptible to being staggered for a critical hit, and I recommend being aggressive with jump attacks or ashes of war like Moonveil's Transient Moonlight or the Bloodblade Dance of Eleonara's Poleblade. I found the Dancing Lion less susceptible to Bleed or Frost buildup.

Divine Beast Dancing Lion has a few attacks where he'll fly into the air and dive back down on you, with one of these being a command grab sort of deal with a long punish animation afterward. It feels bad to get hit with, but I never found it to be a death sentence like Malenia or Astel's grabs from the base game.

Dancing Lion's trickiest move, and one that almost always catches me out, comes at the end of his longest combo, when he'll rear up on his hind legs to use his breath attack in a circle around himself. When he first rears up, it will look like a solid opening for an attack, but I recommend backing off when you see this happen—I almost always got hit when I stayed close in.

Divine Beast Dancing Lion Phase Two

Divine Beast Dancing Lion has three elemental power up s he'll cycle through in phase two, activating the first one—typically lightning—with two thirds to one half of his health bar remaining. His moveset largely stays the same, but each element comes with a curve ball to watch out for:

• Lightning: Dancing Lion cribs from the Ancient Dragon fights of the base game, and will periodically activate an ability where the ground glows briefly before lightning strikes that location. When this happens, I often find myself getting punished for staying in to do damage.
• Frost: Dancing Lion will inflict frost buildup on all of his attacks, especially his breath weapon, and gains a Hoarfrost Stomp-style AOE move you can jump or dodge through. This is his most dangerous mode.
• Air: This is usually when I felt the safest during phase two, though Dancing Lion does gain a homing tornado move that’s difficult to dodge through or outrun.

If it's all a bit too much, you can also summon Redmane Freyja before the boss room. I haven't tested this fight without talking to her at the Three Path Cross site of grace in the Gravesite Plain, but you'll want to talk to her there anyway to progress her questline. 

Keep at it, and the Dancing Lion will eventually fall to you. Once you've beaten him, don't forget to go through the door and up the elevator on the northern wall of his boss room, to your right when facing away from the entrance. You can progress the story just fine without seeing what's up there, but I was missing some crucial context until much later on my first run through Shadow of the Erdtree.