For a debugger, you can use all the tools that are available. I personally use VEH on Cheat Engine and also look through the memory/branching with the Memory View Function Call Branching. I also pair it with Ghidra's Decompiler to jump from place to place. It's all about taking your time to looking through the opcodes/branching. Ghidra's decompiler also helps with making sense of the code sometimes, but you need to really process the information. I would say x64dbg is good, but you need to make sure you have Themidie or ScyllaHide (I think ScyllaHide) to bypass Themida on the MapleStory private servers.
Ghidra: Static Analysis (You don't have to run MapleStory, just pop it in and it will parse the opcodes)
Cheat Engine: Runtime Analysis (Great for when you want to find real-time data. These are things like Amount/Timing/Pet Hunger/Buff Counters/Unlimited Attack)
Good luck on your journey