I play Lethal Prowler from time to time. It wins the game sometimes but sometimes you lose because you have this piece of wood in the hand + Dark Knives and Assassin's Aims and can do nothing. Sometimes, better to have another 4-mana hidden than Lethal Prowler.

Why Heroic Brawler this time... Firstly, my HB is diamond :D Secondly, it can be helpful as well.

Quite often they can't kill it and it starts buffing other creatures - Shadow of Lethenon becomes 2/2 at the end of turn and, thus, becomes safe from many spells. If Switch Duelist gets extra health, you can buff it with AA or hide with god power. Lurker with +1/+1 become something much more powerful.

When under order or sleep, it keeps buffing creatures or itself so this is also annoying for the opponent.

Finishing HB with a relic - which War likes to do to creatures - is painful - if HB is alone, it buffs itself at the end of the turn to 6/6.

It has an anti-Mage specialty - I drop it onto the empty board on turn 6.5 + pip, and hide it with god power. At the end of turn, it becomes 6/5 and nor Shaped Blast neither Unbound Flames can reach it.

Cons - it's 5-mana creature which isn't fantastic for HRD by itself and it has no hidden. Sometimes, better to have another 4-mana hidden, like Lokian or a Shade Walker. Or Lethal Prawler.

Maybe for this reason I am stuck in Solar with visiting Auric from time to time?

Right now I am too tired with this RNG-game and quit aggro Deception with all its rickety minions and switched to Amazons just to learn how it is to play with Divya and Fae Thornblades.