It has the Ability to reduce incoming damage output from opposing enemy Pokemon by 30 if it has any Energy card attached to it and has the potential to actually Knock Out Crobat, Lumineon, and other basic Pokemon V that are still being set up by your opponents with Retaliate
In particular, Aminatou, Veil Piercer surveils every turn, putting Enchantments into the graveyard where Starfield of Nyx can reanimate them, and Marina Vendrell unlocks rooms for free, turning low-mana-value spells into big-mana-value permanents that Starfield animates into huge creatures
Fortunately, the tutorial system here is the most complete weve seen on the DS platform since Yu-Gi-Oh: NT (an otherwise mediocre title)
I think its easy to say that Heartflame Duelist is weaker than a card like Bonecrusher Giant, but that ignores what the card does bring to the table
It's impossible to use on your first turn since you can't load up the Graveyard before using it until your next turn, and by then it's likely too late to make any kind of impact