2) I've not done all the math and from a quick glance most rotation guides are based on high level. Basically, I want to know if I'm meant to go: Impulse Drive>Disembowel OR True>Vorpal>Full Trust. The latter dishes out more damage, so I'm not really sure about the purpose of the former for now. Its only application would be if an enemy is low on health, but that seems more or less impossible to gauge in this type of game.

I've recently been leveling my DRG and made a quick spreadsheet to calculate this exact scenario.

**This is extreme min/max type stuff and really only applies to sub level 60 content.**
Prior to getting Fang and Claw and Wheeling Thrust, the situation boils down to: "If I skip a buff weaponskill (Heavy Thrust and the Disembowel debuff), can I add an extra Full Thrust?" If the answer is yes, then you will want to skip those buff skills and just use True -> Vorpal -> Full Thrust

For example, if we take trash monsters in a dungeon and assume they will live for 20 seconds we can start with:

HT -> T -> V - F -> T -> V -> F -> T -> V for a potency total of 2533

or we can just spam the True Thrust combo

T -> V - F -> T -> V -> F -> T -> V -> F for a potency total of 2580

As you can see, just spamming the True Thrust combo is slightly better. I chose this example because it is also the breaking point where Heavy Thrust becomes worth using. Additionally

**, i**f we factor in Jump and Spineshatter Dive, then in this 20 second window Heavy Thrust adds an extra 47 potency to the first rotation ([260+210]*0.1), which makes both rotations have an equal potency total (3050)! In reality, Jump and Spineshatter Dive have cooldowns longer than 20 seconds, so the second rotation will pull slightly ahead over time.

The TL:DR to the above is:

**If you are fighting for longer than 20 seconds, use Heavy Thrust. Otherwise, just spam the True Thrust combo.**
I'll save you the long winded math for the Impulse Drive combo, and just summarize in a quick TL:DR as well:

The piercing debuff provided by Disembowel is only useful when you get the full duration (aka mostly just on bosses). Otherwise, just use the True Thrust combo spam with the above 20 second rule applied.

**Once you get Chaos Thrust, then you can replace a True Thrust combo at the beginning of a fight if you get at least 3-4 ticks of the DoT effect (about 9-12 seconds of DoT duration). **Make sure the Chaos Thrust debuff is kept up as much as possible on long fights.

Finally, if you have at least one Bard or Machinist in your party, it's very important to make sure you use the Impulse Drive combo, because the piercing debuff also benefits them.