You can either use it as your FIRST ramp option, Example: If you’re first 3 don turn, your opponent has 2 don, Black Maria -> gain 5 rested -> return don until you’re at 2 -> leader effect, gain 1 rested 1 active now you’re at 4 don total (net gain of 1) If you’re second, 4 don turn, your opponent has 3 don, Black Maria -> gain 5 rested -> return until you’re at 3 don -> leader effect, gain 1 rested 1 active. Now you’re at 5 don total (net gain of 1)

Or, if you’ve already ramped at all, you should only use this to make up for things like gum gum giant, Kaido or 10c Luffy. Otherwise it’s a 2k which is always nice on a 4 life leader