You are not able to directly read what they enemy is casting or read what projectiles are currently traveling, but you are able to make educated guesses on what the opponent has cast by watching their current mana and seeing if it changes. Say, if the opponent’s fire jumps down by 15, you know they just cast a fire ball and can prepare a shield against it.
You are able to read if the opponent is building a collector or not by looking at opponent.action.
Keep in mind that you won’t be able to perfectly predict what the opponent is casting as the only times you can run code are when you yourself aren’t casting or building and when a collector chooses its next item. If you are summoning a spell or building a collector, you are mostly blind to the opponent’s actions.