If it dies, well, it was probably dying anyway
Before starting with the most expensive, I want to start with Super Secret Tech, a card that gives a boost in power to all your other foil cards in play
The backside of this card, The Prismatic Bridge, is a WUBRG Legendary Enchantment
Three mana is a lot to generate every turn, and Cormela's access to the haste keyword allows her to provide it the same turn she comes down as long as you have an extra generic mana lying around
It's a powerful answer to a big problem in 'walker-heavy environments from Standard to Commander
A High Market in the manabase, or creatures that have sacrifice abilities, or just an Oketras Monument to provide cost reduction all things that can enable Skullclamp