Yama is widely regarded as one of the most profitable bosses in the game, and for good reason. A single piece of Oplate armor can sell for around 100 million RuneScape gold at the time of writing. Even for Iron Man accounts, Oplate is highly desirable as some of the best-in-slot slash armor. But beyond profitability, Yama stands out for its incredibly well-designed drop mechanics.

In this article, we’ll break down all the ways to acquire Oplate, analyze whether soloing or duoing Yama is better, and reveal why this boss’s design might be some of the best in the game.

Four Ways to Acquire Oplate

There are four primary methods to obtain Oplate from Yama:

Direct Drops: Killing Yama grants a straight-up chance to receive an Oplate piece, similar to other NPCs.

Forgotten Lockbox: This rare item drops 1 in 33 kills. Opening the lockbox gives you another chance to obtain Oplate.

Oplate Shards: Collect 450 shards to craft any Oplate piece. Shards provide a form of “dry protection,” preventing the grind from becoming unbearable.

Contract of Oplate Acquisition: For the most dedicated players, Yama can drop King Roel Files (1 in 12.1 chance), which contain the Contract of Oplate Acquisition (1 in 133.8 chance). Completing this contract guarantees an Oplate piece.

Each of these methods affects the average kill count (KC) required to complete a full Oplate set, and they interact differently depending on whether you’re soloing or duoing the boss.

Soloing vs. Duoing: The Basics

If you kill Yama solo, the odds of getting any Oplate piece are 1 in 200, or 1 in 600 for a specific piece. Using the coupon collector problem, we can calculate the expected KC to complete a full set:

Average KC=200×3×1.83≈1,100

Average KC=200×3×1.83≈1,100

So, purely from direct drops, you’d expect to complete your Oplate set after around 1,100 solo kills.

In a duo, your drop rates scale with your damage contribution. Doing 50% of the damage reduces your odds to 1 in 400 (or 1 in 1,200 for a specific piece). Doing 60% of the damage improves this slightly to 1 in 333.

Time Analysis

Assuming a melee setup:

Solo kill: 6 minutes

Duo kill: 3 minutes

At these rates, the total grind time to complete a full Oplate set is approximately:

Solo: 110 hours (1,100 KC)

Duo 50% damage: 110 hours (2,200 KC)

Duo 60% damage: 91.8 hours (1,800 KC)

This shows that unless your damage contribution is significantly higher than your partner’s, soloing or duoing Yama results in roughly the same total grind time.

Forgotten Lockbox Impact

The Forgotten Lockbox changes the dynamics. Each kill grants a 1 in 33 chance at a lockbox, regardless of your damage contribution. Within the lockbox, there is a 3 in 43 chance of obtaining any Oplate piece. This gives an overall 1 in 4,433 chance per kill for Oplate from the lockbox.

While that seems low, it actually improves the drop rate slightly:

Solo: from 1 in 200 → 1 in 191

Duo 50% damage: slightly better because the lockbox ignores contribution

With the lockbox considered, duoing can actually become slightly more efficient than soloing, as your odds from the lockbox are unaffected by shared damage.

Oplate Shards: Dry Protection

Without Oplate shards, a large portion of players can go thousands of KC without completing a full set. Including shards drastically reduces this grind.

Solo average KC with shards: 641 (down from 1,150)

Duo 50% damage: 1,200 KC (down from 2,000)

Shards create a secondary peak for unlucky players, ensuring that even those who get unlucky don’t face extreme dry streaks. Unlike guaranteed drops, shards offer partial protection while still preserving the randomness and excitement of loot acquisition.

Contracts: The God-Tier Advantage

Completing contracts further improves efficiency. Two contracts are relevant:

Contract of Oplate Acquisition – guarantees a piece on completion

Contract of Oplate Shard Acquisition – boosts your shard collection

For players consistently completing contracts:

Solo average KC drops to 550

Duo 50% damage drops to 1,040

Contracts offer significant time savings for players skilled enough to complete them reliably. 

Why Yama’s Design is Brilliant

Yama’s drop mechanics are more than just RNG—they incentivize teamwork and smart play.

Duo Incentives: Forgotten lockboxes make duoing potentially faster than soloing.

Dry Protection: Oplate shards prevent extreme unlucky streaks while maintaining the thrill of randomness.

Contracts: God-tier players can further reduce grind times, rewarding skill and planning.

Compared to other bosses, Yama strikes a balance between solo viability, team efficiency, and long-term fairness. It’s one of the best-designed bosses in the game from both a mathematical and gameplay perspective.

In conclusion, Yama isn’t just profitable—it’s a masterclass in boss design. Whether you’re going solo, duoing, or aiming for god-tier efficiency with contracts, understanding the math behind Oplate drops can save you hours and make your grind far more predictable. Having enough cheap Runescape gold can also be very helpful.