Arcade Rewards Are Kinda Insane
Ok, so if you clear all the objectives, this is what you get:
3,600,000 million gold
10 research grants
825 units
20k Titan shards
32k 7* shards
2* Doombot
On my main account, I bought the $5 pack and have finished most of the objectives.
On my alt F2P account I'm just going to wait until the daily tokens add up and then just try to get it all done in one session.
Overall, I don't find the mode very engaging, but the rewards are pretty insane, even if you spend money, and you can just have it autoplay while doing something else.
I did enjoy filling up the masteries, that was kinda fun, especially compared to the real masteries, where it takes months to get an extra point.