To beat down with the lovable Rat Colony

Garna, the Bloodflame seemed great for a deck built around Ray Colony since she gets to protect you from devastating board wipes, as well as giving your creatures haste on your turn.

Bontu's Monument is used to make our rats cost B, and the added drain is also nice.

Gate to the Afterlife might be too cute, but it's included since our rats will be dying most likely, and we can get some additional value off of Garna, if we discard creatures to the effect, and get them back with her.

God-Pharaoh's Gift goes in since we're already playing gate, and making 4/4 Rat Colony seems dece.

Secret Salvage is another dash of spice in this deck. It allows us to get as many rats as we want to our hand. With the additional spice of Secret Salvage + Colony Rat + Fateful Showdown all for the low cost of 5BBRR.

This might be too cute, and it's probably correct to just play another Colony Rat over Fateful Showdown