If Worldfire and Coalition Victory can be legal cards without messing up the format too much, so can Biorhythm
If you like your friends but would prefer they talk less: Try The Crew: The Quest for Planet Nine, a cooperative trick-taking card game that drastically limits conversation at the table
Wound Reflection, Warlock Class, Bloodletter of Aclazotz, and anything worded like this doubles your damage, which is sometimes enough to one-shot players with commanders like Heartless Hidetsugu or Alpharael, Stonechosen
A sort of tingling sensation
There are 138 Green and Black Insects, which gives you enough for a Commander deck but not that many options
Crystals are usually depicted as being sentient and will even be able to speak with the user, in a gameplay technique that allows the narrative to continue moving forward