The top Grand Warden loadout is Eternal Tome + Fireball. Full tier list, best 2-slot combos and upgrade-stop levels below.
A force multiplier — his equipment buffs the entire army marching near him, not just himself.

Every piece ranked S to F for the current meta. S-tier earns your Ore first; F-tier should never be upgraded.
You equip two pieces per attack. These are the strongest pairings by situation.
You don't unlock everything at once — common pieces come from the Blacksmith, Epics from events and the shop. Here's the loadout to run as you progress.
The Grand Warden unlocks at Town Hall 11 with Eternal Tome; Rage Gem unlocks here too. Eternal Tome + Rage Gem is a strong free-to-play start.
Epic caps reach 18 at Town Hall 12 — Eternal Tome + Rage Gem remains the best free Warden pairing until Healing Tome unlocks.
Healing Tome unlocks (Blacksmith Lv6) — Eternal Tome + Healing Tome becomes the best all-round Grand Warden loadout at Town Hall 13.
Common reaches Level 18 at Town Hall 14; Eternal Tome + Healing Tome carries every ground push.
Epic caps hit 24 at Town Hall 15 — Fireball finally becomes viable. Eternal Tome + Fireball (Level 24+) is the war goal.
At Town Hall 16, a Level 24+ Fireball one-shots compartments — Eternal Tome + Fireball is the ground-smash meta.
Eternal Tome + Fireball is the top Town Hall 17 Warden loadout; Eternal Tome + Healing Tome is the safe all-rounder.
At Town Hall 18, Eternal Tome + Fireball for ground smash, Eternal Tome + Healing Tome when you want guaranteed sustain.
What each piece does, its tier and rarity, and the level to stop upgrading at.
~8 seconds of full damage immunity for the Warden and nearby troops.
Large burst heal to nearby troops — the best Common healer.
Always-on +50% damage to nearby friendly units.
Compartment-nuking AoE — only viable at Level 24 and above.
Passive HP buffer to nearby units — reliable for ground smash.
Movement speed + damage resistance during the approach.
Summons Lavaloons; the worst Epic investment in the game.