Five mana is a lot for this sort of ability, however
The cards going out are just as important as those going in
The main rules are simple: Pick a Legendary Creature as your Commander Only cards of your Commanders color identity are allowed in your deck Youre allowed one copy only of any card except basic lands 100 cards per deck You start at 40 life If you want to find out more, you can visit WotCs page on Commander
You get the artifact creature master with Urza, Chief Artificer, the gargantuan The Capitoline Triad, who fuels historic synergies and encourages you to play massive artifacts, and then Imskir Iron-Eater keeps your artifacts going with a strong draw effect when it comes into play
This is great news and will help the deckbuilding in these colors go a little bit smoother
If you pick up a couple of UR/UB duals and a World Map, you could use those to splash the powerful Shantotto, Tactician Magician, which plays incredibly well with those spells