Being able to power out a turn four artifact that ramps, gains you life, grows your creatures, AND draws you cards is way too much
I dont find Thundering Spineback particularly tempting, however
The trigger event doesn't have to specifically refer to legendary permanents or to artifacts, nor does it have to specifically refer to when something "leaves the battlefield." For example, an ability that triggers "whenever a creature dies" would trigger twice if a legendary creature or an artifact creature dies while Gandalf the White is on the battlefield, as would an ability that triggers "whenever a permanent is put into a graveyard from the battlefield." Look at each legendary permanent and each artifact as it exists on the battlefield, taking into account continuous effects, to determine whether any triggered abilities will trigger multiple times
Black Lotus, Mishra's Workshop and Tolarian Academy are all auto includes if you can get them in the archetype but they are also all a little bit overkill
Viral Drake Viral Drake is a flying infect creature with a higher-than-normal toughness of your usual infect creatures