I'm pretty sure most people are having trouble on taking care of Alocasia in their home. Mostly they died from rot or pest issues. Let's discuss the most common problem which is rotting.
Rot usually occurs when:
1) the medium is too wet (not well draining enough),
2) pot size too big for the plant (excessive water retained),
3) high humidity with low or no ventilation (water settles on leaves or can't evaporate into air).
It can be any one of the reasons above or a combination of those reasons that makes your plant rot. This applies to most of your plants as well. So to solve those issue, you need to know your environment condition which includes light intensity, humidity level, and air ventilation. Understanding your condition helps increase the chances of your plants surviving.
After knowing your conditions then comes choosing the right medium and pot size for your Alocasia. Depending on the species, each of them requires different level of light, humidity and soil moisture level.
The usual mix for my Alocasia are 60% Pumice (40% of fine grain + 20% medium coarse grain) , 40% fine sifted premium coco peat. This is well suited to my condition and watering schedule. Do feel free to adjust or change your soil medium depending on your condition as well.
Given example for Alocasia 'Stingray', which is a cultivar of Alocasia Macrorrhiza. It likes to be under partial or fun sun and need a well draining soil mixture for healthy roots to grow the plant. So if you are growing it in indoor space, make sure it gets adequate amount of light for it to thrive, and best if you growing it outdoors. It doesn't requires high humidity to thrives but best to give it at least 50% to help combat our second issue with Alocasias: spidermites.
Pests can be a nuisance for a plant parent. In case of Alocasia, it would be spidermites. Those tiny red mites that moved around on the leaf is sucking the nutrients out from the plant cell. You'll notice white spots are formed when there are spidermites damage.
In early cases of noticing them, its easily manageable by wiping the leaf along with the spidermites with soapy waters and keep in observation for about 10 days and wipe the leaf with soapy waters again every 3 days. It's best to quarantine the infected plant so that it wont spread to your other precious plant babies.
Often when we notice that when we have spidermites on our Alocasia, it will be an outbreak where the whole plant is infected. Webs are covering the leaves, new leaf are smaller and even damaged before hardening are signs of spidemites infestation on your Alocasia. During this time, we suggest that you clean the whole plant with soapy waters, cut all infected leaves, and spray the plant with miticide (either chemical or organic) whichever you prefer. Repeat spraying it with miticide every 3 days for at least 3 times or until no mites are found.
Prevention measures can be taken with increase humidity levels and weekly pesticide (chemical or organic) application is advised. Remember prevention is better than cure.
I hope this helps you on better taking care of your Alocasia.