It's the planeswalker clause here that really pushes things over the edge, moving this into Hero's Downfall territory for a scant two easy to cast mana
While things have changed over the years, this particular card is still a favorite among many long-term players
There are multiple very relevant threats which survive Lightning Bolt but die to Heat, such as [card]Yawgmoth, Thran Physician, Omnath, Locus of Creation, Crashing Footfalls, Primeval Titan, most Planeswalkers, Yorion, Sky Nomad, and the list goes on
For two more mana, you can bring back two creatures with a total mana value of four or less from your graveyard and put them in play
Overall Garth is a cool, fair 5C commander with a unique oldschool vibe that I respect