You can't choose card types (e.g., artifact), supertypes (e.g., snow), or noncreature subtypes (e.g., Aura)
However, there is a sort of structure you can add to your deck building process that may help
Its easy to set up delirium in decks that want to, and you can have a win condition based on the number of spiders you have, making Iskkanah a solid delirium commander
Umori, the Collector Choosing creature with Umori, the Collector makes all of your rats cheaper to cast, making it a natural commander for Rat Colony
Acquiring this card sooner rather than later seems to be a smart decision for those who wish to play this card in paper
Besides giving you twice as many tokens as youd normally give yourself, this plays well into any of the councils dilemma or will of the council effects you can slam into a Tivit deck