lol, do you have any idea how hard that is? just the accounting aspect of international tax is hard.
there are 3 layers you have to consider
1. the accounting layer
2. the tax code layer
3. the legal layer
you would need a top14 law school JD and a top3 tax LLM to become a biglaw tax lawyer. a big4 accounting firm lawyer would need a JD/CPA/taxLLM combo to be international tax. it is possible to have a JD/taxLLM combo in the big4, but it would generally not be in international tax.