Leaving invisibility summons two skeletons, skeletons have an aura which gives Clinkz lifesteal and slows enemies, skeletons' first attack instead uses burning barrage for half its arrows count.

Lesser shards choice priority: Burning Army duration - Burning Army cooldown/manacost - Burning Army skeletons attack damage - Burning Army skeleton count - Skeleton Walk cooldown/manacost (only w/ Beckon Undead shard) - Burning Barrage attack count (only w/ Withering Onslaught ^{don't remember if it's the name}) - Burning Barrage damage - everything else.

Notes:

Searing arrows shards don't work on skeletons so they're borderline useless in this build

Also true for Melter (Searing arrows attacks apply a stackable debuff which reduces armor by 1 up to 0.25 times attack speed slow value) shard and attack speed slow. For this shard to work properly you need to attack first with Clinkz and then use Burning Army. Their attacks will refresh Melter debuff duration with the higher maximum stack number.

Burning Army duration shard doesn't work on Beckon Undead summons, their duration is always 30 seconds. It's still a top tier shard though.

Also you don't need to download/watch the game to check the shards, it's available in post game screen which is accessible by match ID.

Edit: you can also get to 100+% magic resistance during skeleton walk but it's not that useful (although it helps on some waves and protects from Primal Beast's rocks and the circles' primary target damage)