Speaking of sacrifice outlets, Master of Dark Rites turns any creature you control into a Dark Ritual
Take our example, where we have our [c]Blightsteel Colossus[/c] and our opponent attacks with the [c]Worldspine Wurm[/c]
Note that this doesnt care about who controlled the creatures that died, so you can throw a bunch of tokens into your Viscera Seer to set up a huge swing of card advantage
You get Nikya but with a little bit of a restriction: you can only cast creature spells, which is fine, since Gruul is known for its wide variety of creatures, and Nikya lets you play all of them
Icebreaker Kraken is a beast of a creature, but with the math on Snow lands for drafting, on average you will have this on the battlefield on turn eight
Of course, Otter-Penguin costing one more mana and not gaining its evasive buff permanently are two major downsides when compared to Delver