Compared to certain generic mechanics like raid, populate is very restrictive where its good
This is a good top-curve because it's imposing when it comes down and can remain a threat late thanks to exhaust
9 Helga, Skittish Seer Cast Those Baddies Casting big ol' creatures is always a blast in commander so why not play a commander that rewards you for doing so
The leftmost and rightmost Spell & Trap Zones can optionally be treated as "Pendulum Zones" by placing Pendulum Monsters there, allowing players to use Pendulum Effects and perform Pendulum Summons
Grenzo, Havoc Raiser is also great, but doesn't really fit the overall theme and it's not likely you'll have two red mana to cast it on your second turn with just 15 lands producing red mana (we'll add more, but it's still not a great price for an early-game play)
World Championships 2013 has 0 cards worth $100+ here are the top 20, with what each is worth graded