I know a lot about this card, so i'll explain as best I can how it works:
Oracle Text:
If a player would draw a card except the first one he or she draws in his or her draw step each turn, that player discards a card instead. If the player discards a card this way, he or she draws a card. If the player doesn't discard a card this way, he or she puts the top card of his or her library into his or her graveyard.
This is a replacement effect. So if multiple ones are in play, you choose which replacement effect you want to use. You can only pick one replacement effect for each action. However, if you draw a card this way, the clause on the other one hits and a second replacement effect happens. "...that player discards a card instead. If the player discards a card this way, he or she DRAWS a card" that draw on the Chains #1 is the trigger for the Chains #2.
So the stacking effect only happens if you are drawing a card, and not if you are milling. You never get to stack mills because there is only one replacement effect.
Other interesting situations arise when you have a dredger in the graveyard. If that player has a card in hand, they have a few choices:
- They can dredge as a replacement effect and discard no cards.
- They can discard a card to Chains of Mephistopheles, then trigger the dredge ability when Drawing a card off of chains resolution (you would do this if you wanted to dredge but had no dredgers in your graveyard)
- You can choose not to dredge.
last edited by gkraigher