Graves
Source: Promotion. In one invasion of the Haunted Mines, a team of heroes only managed to collect a single skull. The golem that resulted, too small to do much damage... Undead type. Some tips for gaining player levels quickly: While you can gain experience in Practice mode without playing against other players, it is faster to play on an actual team.
Graves is a promotional battle pet obtained by reaching Player Level 20 in Heroes of the Storm, a free-to-play game.
Guide awaiting review
Download Heroes of the Storm
Heroes of the Storm is free to play, so you can download and play it at no cost all the way through Player Level 20 to unlock Graves.
Level up efficiently
Play Quick Matches against real players rather than AI matches, as games versus AI yield substantially less experience. Playing with a friend grants a 50% experience bonus, and Stimpacks increase experience earned per match by 100% — a 7-day Stimpack costs $3.99 and a 30-day one costs $9.99. Experience boosts stack additively, so combining them speeds up progression significantly.
Reach Player Level 20
Once you reach Player Level 20 in Heroes of the Storm, Graves is unlocked and delivered to your World of Warcraft account. Based on player reports, reaching this level with a Stimpack and friend bonuses active took approximately 47 games averaging 20 minutes each, totaling around 16 hours of playtime. Blizzard has not announced an end date for this promotion, so it remains obtainable until otherwise stated.