Magic is a very complex game. Maybe the most complex game known to mankind. As shown in https://arxiv.org/abs/1904.09828 Magic is turing complete. Some games are solved https://en.wikipedia.org/wiki/Solved_game
for some games breakthroughs have been achieved in the past years where computers can now surpass humans e.g. chess, go.
It would be interesting to do that for magic.
There are many benefits in doing this:
- Its fun and challenging to write code that competes with others.
- Organizing competitions can attract new customers (programmers) to magic.
- People can later analyze their games with engines and find mistakes as chess masters do.
- Tutor engines can be written that help new players.
- Interactive magic puzzles can be made (same as in chess find mate in 3)
- Single player offline mode.
- Future Future League balancing simulations. Resulting in less broken cards and happy customers.
- Commentators can have indications on who is winning the game, what are possible topdeck outs what is the probability (as in poker)
Many other companies already recognized that opening up an API to the public benefits their games. In recent years professional gamers played against Starcraft and DOTA pros. Resulting in exiting matches of mankind vs machine.

So create an API that gives only 3 things:
- current game state
- possible moves
- choose a move
and you are done ;-)