For true craziness, you can copy creatures that pump each other, trigger on combat damage, or have have abilities that trigger whenever something happenseach copy sees the others enter the battlefield and deal damage, so your triggers grow geometrically
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Legendary Creature - Human Knight Faramir, Field Commander At the beginning of your end step, if a creature died under your control this turn, draw a card
A legendary artifact that costs zero mana, it fits perfectly into Commander decks as a free Arcane Signet
An extremely busted Dinosaur payoff and a kill on sight threat in Commander
The Wandering Rescuer sports a very clever design: Convoke helps you cast this creature, but also taps your creatures down to pick up hexproof from The Wanderer