Arena focuses so hard on incentivising the player to spend money on it that it's very hard to actually play Magic. Magic the Gathering is. at its core, a tabletop card game that you play by building a deck and playing against other players who have also built their own decks, starter decks aside. Notice how most of that was focused on building a deck? Let's get into that process.
You have two main routes to obtain cards in Arena; opening packs, and crafting specific cards.

The way you obtain packs is through a number of ways. Getting gold from daily win rewards and using that gold to buy packs, completing daily quests for a larger reward of gold (such as casting a specific color of spells, killing creatures, eta.), obtaining them from the battle pass, or just simply purchasing them from the in-game store for Gems. Gems are a currency that, as far as I can see, you can only obtain by purchasing them for real world money, receiving them as a reward from an in-game tournament (that you have to pay Gems to enter in the first place) or through the battle pass (which, it's only on the paid for, upgraded version of.)

Now that the pack system and how to receive packs have been explained, we enter in the second way to obtain cards; crafting them with Wildcards. Wildcards are "cards" that you receive from opening packs by random or by opening a certain amount of packs, there is a wildcard for each rarity of card. You can use them to craft specific cards, an example would be using a Mythic Wildcard to craft a Teferi Planeswalker card. You can also purchase them from the store, with real world money or with Gems, I believe.

Now, this poses an issue from a player standpoint. When you run out of packs to open, you run out of quests and gold to cash in and have to wait 24 hours for more, and you run out of wildcards; how do you get cards?

Making decks, playing around with specific cards, and brainstorming is an important part of Magic. It's literally half the game because it's a card game, in my opinion. Arena essentially time locks you every day in this way; you literally cannot obtain anymore packs, cards or wildcards after you run out of gold and have to wait 24 hours. Unless you spend money.

Arena gridlocks you. It tells you up front "if you want to make a deck that you enjoy playing, you need to dedicate ten or hundreds of hours of your time opening packs and hoping you get the cards you want or enough wildcards to craft your deck. This can be instant if you pay real world money for wildcards or packs. Good luck if you play standard."

I do not recommend Arena. It doesn't even feel like a F2P game. At least most F2P games supplement the grind and payment incentives with, like, proper gameplay. This doesn't feel like that, it feels like you get a free trial every day to try Magic before you get a pop up telling you to pay for the full game.

If you are looking into getting into Magic the Gathering or simply want to play the game, this ain't it chief. My personal suggestion would be; simply go to your local game store, there is a thing called Friday Night Magic that is endorsed by Wizards of the Coast (funnily enough, those are the guys behind Arena.) that you can actually locate by using the Wizards of the Coast FNM tracker. Go there, grab your decks, or buy a prebuilt deck, and just play there. It's so much better.

If that's not an option, use Cockatrice. It's a pain in the ass and everything is manual, and it looks like ♥♥♥♥, but it's better than this. Alright, schizophrenic rant over.

Arena focuses so hard on incentivising the player to spend money on it that it's very hard to actually play Magic. Magic the Gathering is. at its core, a tabletop card game that you play by building a deck and playing against other players who have also built their own decks, starter decks aside. Notice how most of that was focused on building a deck? Let's get into that process. You have two main routes to obtain cards in Arena; opening packs, and crafting specific cards. The way you obtain packs is through a number of ways. Getting gold from daily win rewards and using that gold to buy packs, completing daily quests for a larger reward of gold (such as casting a specific color of spells, killing creatures, eta.), obtaining them from the battle pass, or just simply purchasing them from the in-game store for Gems. Gems are a currency that, as far as I can see, you can only obtain by purchasing them for real world money, receiving them as a reward from an in-game tournament (that you have to pay Gems to enter in the first place) or through the battle pass (which, it's only on the paid for, upgraded version of.) Now that the pack system and how to receive packs have been explained, we enter in the second way to obtain cards; crafting them with Wildcards. Wildcards are "cards" that you receive from opening packs by random or by opening a certain amount of packs, there is a wildcard for each rarity of card. You can use them to craft specific cards, an example would be using a Mythic Wildcard to craft a Teferi Planeswalker card. You can also purchase them from the store, with real world money or with Gems, I believe. Now, this poses an issue from a player standpoint. When you run out of packs to open, you run out of quests and gold to cash in and have to wait 24 hours for more, and you run out of wildcards; how do you get cards? Making decks, playing around with specific cards, and brainstorming is an important part of Magic. It's literally half the game because it's a card game, in my opinion. Arena essentially time locks you every day in this way; you literally cannot obtain anymore packs, cards or wildcards after you run out of gold and have to wait 24 hours. Unless you spend money. Arena gridlocks you. It tells you up front "if you want to make a deck that you enjoy playing, you need to dedicate ten or hundreds of hours of your time opening packs and hoping you get the cards you want or enough wildcards to craft your deck. This can be instant if you pay real world money for wildcards or packs. Good luck if you play standard." I do not recommend Arena. It doesn't even feel like a F2P game. At least most F2P games supplement the grind and payment incentives with, like, proper gameplay. This doesn't feel like that, it feels like you get a free trial every day to try Magic before you get a pop up telling you to pay for the full game. If you are looking into getting into Magic the Gathering or simply want to play the game, this ain't it chief. My personal suggestion would be; simply go to your local game store, there is a thing called Friday Night Magic that is endorsed by Wizards of the Coast (funnily enough, those are the guys behind Arena.) that you can actually locate by using the Wizards of the Coast FNM tracker. Go there, grab your decks, or buy a prebuilt deck, and just play there. It's so much better. If that's not an option, use Cockatrice. It's a pain in the ass and everything is manual, and it looks like shit, but it's better than this. Alright, schizophrenic rant over.