Summon and attack damage

Bodyguard grows Osty’s HP reserve. Unleash turns his current HP into additional damage, so protecting or rebuilding him affects both the defensive turn and the attack. Bound Phylactery supplies recurring Summon, but a small return at the start of a turn is not the same as a large reserve ready for a boss attack.

Osty’s attacks do not use the player’s Strength or Weak. Calcify directly improves his damage instead. This makes player Strength penalties less costly to an Osty-focused attack plan, while also making a generic Strength bonus less useful than it would be for ordinary attacks.

Sequencing the attacks

Fetch and Poke are inexpensive ways to begin an Osty sequence. Flatten can become free after Osty has attacked that turn. Rattle adds hits for earlier Osty attacks, so playing it before the small attacks wastes part of its possible payoff. Keep the order visible when several cards are in hand.

Sic ‘Em makes further Osty hits against its target contribute Summon during the turn. A sequence with several attacks can therefore support his health as well as damage. Do not assume the result against a group is the same as repeated hits directed at one marked target.

Defense against debuffs

Hunter Killer can make ordinary attack damage awkward through Strength penalties. Osty’s independence from the player’s Strength provides a different attack route. Do the defensive calculation first, then check which attacks still contribute the damage needed. A player’s weak-looking attack statistics do not prove that an Osty card is weak too.

Spur can help sustain an existing Osty plan, while Invoke prepares resources for the next turn. Reanimate provides a large Summon effect at a substantial energy cost and Exhausts. The reserve it creates must be weighed against the attack or defensive cards that cannot be played with the same energy.

Upgrades and missing pieces

A Bodyguard upgrade strengthens an action already in the starter deck. Calcify becomes more attractive when the deck repeatedly attacks through Osty; collecting it before finding enough attacks can instead add setup without a payoff. A draw improvement can help both components meet in the same hand.

Bone Shards deliberately kills Osty after its effect. Count which remaining attacks require him before using it. If the run does not supply enough attack support, keep Osty as a defensive package and use Souls or Doom for damage. That is a useful pivot, not a failed version of the original plan.