Trying to help husband come up with “achievement” quests

Hi! Basically the title.

My husband is having his group over to play commander in a few weeks and he wants to have secret achievements for players to do thought the game. Whoever finishes the most tasks by the end of the night will win a prize (probably a collector booster).

These can be in game and out of game tasks like
-sacrifice a land
-get another player a drink
-deal exactly 9 damage to an opponent
Etc.

These tasks will be distributed in “dossiers” using a kind of spy theme. Each player will have one secret ally and two secret targets that they need to figure out throughout the game.

Each player will be notified of a couple of the tasks their ally and targets will have to help them figure out who they are. This is to encourage the game to go on longer and not have someone instant kill every other player while also adding an element of mystery.

My ask for y’all:

What kind of tasks should he include? I’d like to help him with ideas but I don’t know a lot of specifics about MTG and things that would be achievable without taking fun away from the game.

These are all men in their 30s and coworkers, if that matters.

Any other suggestions are welcomed!