Planeswalkers are not creatures, so deathtouch does not destroy planeswalkers any faster than regular damage
A fully stacked Ring-bearer can be hard for your opponents to deal with, so this could be an interesting build
For true craziness, you can copy creatures that pump each other, trigger on combat damage, or have have abilities that trigger whenever something happenseach copy sees the others enter the battlefield and deal damage, so your triggers grow geometrically
An extremely busted Dinosaur payoff and a kill on sight threat in Commander
Since they will each have a large individual impact, you don't need to necessarily cast a lot of thembut the second one tends to seal the deal
A legendary artifact that costs zero mana, it fits perfectly into Commander decks as a free Arcane Signet