Discard commanders often engage in wars of attrition
Grappling Kraken To maximize Grappling Kraken you want to spend green mana, but even without the extra land drops that are possible with green, the free tap and stun is quite good
Another example is with Sagas
II Put a number of +1/+1 counters on target creature you control equal to the mana value of the exiled card
The late-game card, Cloud of Darkness can remove a pretty big creature once your graveyard is full, and poses a nice threat to your opponent's life total thanks to its Flying ability
For three mana, Fraying Sanity is a Blue Curse that reads, At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn. As above, thats great if youre in mill, but kind of rubbish otherwise