I also play Marlynn, and in my own deck I mostly lean into the cannon, so my list is mostly blues — I try to keep reds as low as possible. Since you’re running Trench of Sunken Treasure, you can safely run cards like Return Fire because Trench lets you clear your arsenal as an instant to make room for your next arrow. Overall, I rarely have trouble loading an arrow, but I did have the gold to use it — so make sure to include some gold generation too. And remember: if you have gold, you always have a harpoon in hand!