After spending the past month or so farming the HoT map currencies, I thought I would share what I found to be efficient methods for each map. I will point out that some aspects will be frowned upon such as "tag & run" similar to what we saw during the SW breach event when it was first released.
If you do a full day cycle, you should get a considerable amount of crowbars. I believe I was averaging around 60 but this also included hopping to the different areas to do those events. If there was a long event, I would hop to another event or two and then come back to complete that event.
I personally saw no benefit to defending camps as the difference between the final meta chests is minimal with defend events not providing any currency or crowbars. I usually spent this time farming airship cargoes. I will point out that if you're on a map specifically going for T4, we considerate and do help out.
For the bosses, each one counts as an event (frogs together count as one) which yields something like 25 currency plus a bunch of crowbars from the bouncy chest. I did not verify if it behaves like those of the daily world boss ones. The actual chests that spawn near the bosses reward some currency occasionally but it's generally a trivial amount.
You can do one of two things to be efficient:
Whichever you choose, you'll still get that bouncy chest as there's no diminishing timer attached to it like event credit. Alternatively, you can do the night meta up to five times if you don't want to tag although you'll more than likely get at least two. Matriarch tends to go down first with it being a toss up between Tetra, Frogs, and Axe. Patriarch is normally last because of the shield phase and how quickly it gets scaled up.
You'll probably earn about 1.5K currency for your first meta of the day and then closer to 1K for subsequent ones. This is assuming that all keys earned are used.
I actually skipped these as they didn't feel worth the time it took to do the events to what I received.
Challenges & Octovine
There's no diminishing timer for this meta, including the mordrem defend events at each side that start at around 11:48 on the timer, which means that you can participate in one burn phase, AFK, and get full event credit and rewards. You can also go back to doing the events I'm describing in the next paragraph. That said, this is highly frowned on and please be considerate to your map if it's struggling.
I usually farmed the Veteran Vinetooths and those priory escort/cleanse events as they rewarded at least 10 map currency. Each side has a veteran vinetooth and the priory events are mainly on the east side. One tip for the vinetooth when trying to solo it is to run through it right as it does it's first attack of it's scripted attack phase. The AI is fairly terrible that you can avoid all damage if you're timing is perfect but in most cases you'll only take damage from the first attack. It does two swings, a tail attack, a charged tail attack, re-targets, and then repeats the attack script. I also tagged each of those four mordrem defend events to stock up on keys. Once the meta completes, use up all of the keys. It takes about 27 to open up all of the chests. You can do the prisoner and HP if you'd like.
You can get around 500 per meta at least.
This is probably one of the harder maps for people and I found the Gerent meta to not be worth the time spent. Lane events give the chak acid to open the caches. This can reward some currency but I personally didn't focus on earning these. If you have them, use them. You may get lucky and they'll contain 30+ ley-line crystals. You also need to open them if going for the HoT legendaries as they're you're main source for ley-line sparks.
My primary source of ley-line crystals was from doing the events that pop up after the lane events are done. These reward at least 10 crystals but I have gotten up to 50 sometimes. The group events tend to reward more by default as I always got at least 25 but this of course requires other people. Most of the events can be done solo. The more events that you do over a longer period of time, the more currency you'll earn. This means don't focus on ones that take forever and try to get on a map that has completed the lane events already. The latter will be easier said than done. If for some reason there's a zerg doing those events, just tag the one they're doing and move on to the next since they're going to scale it too much. The bouncy chests are not subject to that diminishing timer like the event credit nor is the loot itself impacted. You'll get full loot regardless as to whether it is a gold, silver, bronze, or plain chest.
You can get over 1K per meta cycle but you'll probably average between that and 500.
Pods are the only way you're going to get ore and buying the machetes is the most efficient way. Start by completing as many of the warm up events as you can to get your participation up. Obviously tagging them and moving on to the next yields more. This usually isn't an issue as maps don't have difficulties doing these except for that one at south that scales up easily. If you have at least 80% participation, you'll receive full meta progress rewards. The diminishing timer for the meta participation starts at around 30 minutes.
I forgot what my count was but I was opening close to 100 pods per meta. Pods spawn as the meta progresses and even in parts of the lanes after you already passed them. It's nearly impossible to get them all after Mordremoth unless you're a thief. This means you'll have to get some, or all the ones available, before you kill him. North and Mid tend to have downtime while waiting on South. You can use this to get pods. Alternatively, you can start farming them at 30 minutes into the meta regardless as to the progression status of your lane. Again, this will be frowned upon.
South and north are pretty straight forward. Just start at the beginning and run down the lanes. You'll see the pods and you run down as they're hard to miss now that you can see them through walls. Mid will take longer and you'll want to check down below at the first camp, including further towards south. At the second camp you'll want to check both towards north where the wyverns are and then towards south. After the tower phase, 1-2 pods often spawn below the towers. After Mordremoth is defeated, you can go to north's second camp and do the revealed area there along with the one further down with the tigers. There's also the spot at south with the spiders (the HP is there) as well as at the second camp of mid with the mushrooms (also an HP there). If you still have time, sweep the lanes for the new pods that spawned.
You should get at least 120 ore per meta with upwards to 200 if RNG is good to you.