For two mana, you now have a two-turn win on board, assuming your opponent doesnt destroy it immediately
Since dashing is still casting the spell just for a different cost, you still add the appropriate commander tax onto the cost that you pay when you dash based on how many times you already cast the commander
Have you ever built an EDH deck around rolling dice
Golgari Guildgate doesnt have much value in Modern and Commander
Wilhelt , is the deck's Commander, and it can sacrifice a Zombie to draw a card, and then make a 2/2 decayed Zombie token
Start Your Journey Until end of turn, any time you could activate a mana ability, you may pay 1 life