Then theres special hybrid mana symbols, like the ones in Shadowmoor that allow you to pay generic mana or a single colored mana, resulting in something like this:
A 4/4 for four mana in Green with an ability meets the Ravenous Baloth Test of Value
Basically, you use Bant to self-bounce with Fleetfoot Panther and trigger Equilibrium to bounce opposing stuff
When we cast Recross the Paths, we'll stack Grist, the Hunger Tide on the top of our deck
That first ability resembles the shenanigans you can get up to with Dargo, the Shipwrecker, so in the right deck, you can cast it for two mana, attack for seven (that can only be blocked by legendary creatures), and then sacrifice it to destroy an annoying artifact or creature
This cheap red card allows the player to sacrifice any creature they have to deal 1 damage to any target, and Goblin decks always have expendable 1/1 creatures to spare for this effect