Moldorm only takes damage when hit on the sphere at the tail end of his body, and has a total of 7 HP. A common way to defeat him is 1 sword slash followed by 3 spin attacks.
Do a regular sword slash first. Charge a spin attack as he is spinning around in place and carefully dodge him to land that spin attack on his weak spot. The Hammer can be used instead of spin attacks, as it deals the same amount of damage to Moldorm, but the hits can be difficult to land correctly.
The first hit can also be easily delivered with the Bow, which does the same ammount of damage as a spin attack. Two spin attacks then follow and a single slash will end the fight.
The Hammer is the fastest way to defeat a Stalfos, as it will kill it with a single blow. By running past them when first entering the room, there is a chance they will group up enough for you to be able to kill more than one per attack. 2 or 3 uses of the Hammer are usually enough to clear the room.
The Bow (or Hookshot) can be used to activate a red/blue wall switch in the first room of the dungeon while Link is on it. This saves having to use the Hammer on a spring, and merging into a wall to reach the same area.
A spin attack with Link facing left (and potentially other directions?) can also work, but is riskier because you will be pushed off the wall if the attack hits one of the enemies nearby.
By performing a Bombrod on 3F, it is possible to get inside the walls of the dungeon and make your way up all the way to 6F (and even higher to 9F, but that isn't efficient), skipping both platform rides and the miniboss room. A good position to perform the Bombrod is right of the north wall switch.
It is possible to skip almost the entirety of 4F and 5F, including the platform ride, by performing an easier version of the Bombrod. To do so, you will need to get hit by a Crow while at the top height of a Tornado Rod use. First, you will need to lure a Crow to the correct spot:
By performing a Bombrod on 7F, it is possible to clip into 8F and skip one Small Key and a few platform rides.
Once in 8F, step into the warp and you'll be taken to 9F to fight the Flying Tiles like normal. This is one of the hardest Bombrods in the game to perform and is not done in normal speedruns due to it's difficulty.
By performing a Bombrod on 10F, it is possible to skip hitting all the switches in the room to lower the platform with the Mole.
You'll clip into the platform above you on 11F, skipping lowering the platform.
The 10F room can be completed faster by efficiently using the bow to activate some of the switches, instead of walking over to all of them. Some diagonal shots are also possible.
The optimal way to complete it is to stand on the bottom left corner of the elevator as it is going up, shoot an arrow straight north when you reach 10F, move south and perform the diagonal shot seen in the picture above and hit the switch on the right with you sword. You can then make your way near the next elevator and shoot the remaining switch with your bow once you're there.
This way is only optimal if you haven't done the Miniboss Skip. If you've done the skip, then you won't have enough energy / won't be coming from the correct place to do it that way.
Normally after defeating Moldorm, the Pendant of Power will not spawn until you have either collected the Heart Container or have waited a certain amount of time. These things can be avoided and the animation for spawning the Pendant can be skipped entirely.
This is done by simply falling down to 12F, the floor right below the boss platform. Once there, hammer a Mole and return back to 13F to find that the Pendant of Power will now be spawned.
Due to multiple tricks and glitches, it is possible to reach and beat Tower Of Hera without merging a single time, meaning it is possible to beat it as the first dungeon, before ever entering Eastern Palace.
To get past the 1F room, you will have to combine a Recoil Jump with a Bomb Boost. Stand on top of the right raised blue wall, as far as possible in the bottom right corner. Place a Bomb north of where you're standing just before the spiky spinning enemy starts moving north, charge a spin attack facing east and release the spin attack as the bomb is about to explode.
If done correctly, the spin attack will recoil off the spiky enemy, Link will start a jump animation (because he is standing so close to the edge of the wall) and get hit by the bomb explosion, which will boost him south over the small ledge.
Once you reach 3F, use a bomb to activate one of the wall switches to lower the walls surrounding you. From there, perform the Miniboss skip to go from 3F to 9F and avoid all other areas that would require you to merge.
Sadly, beating Tower Of Hera before Eastern Palace doesn't do anyything special. If we could also beat House Of Gales without merging, it might be possible to skip Eastern Palace entirely and go directly to Hyrule Castle. However, even if that was the case, you would still need to merge in order to enter the portal to Lorule to continue on with the game.