Quick Answer: Imaginarium Theater S15 (September 2025) can absolutely be cleared with F2P one-team strategies using Pyro, Hydro, and Dendro characters. You'll want to focus on Vaporize or Burning teams with trial characters like Hu Tao and Xingqiu, manage that Vigor system smartly, and leverage the 20% stat buff for Opening Characters to achieve full clears.
Understanding Imaginarium Theater S15 Mechanics
Imaginarium Theater Season 15 runs September 1-30, 2025 (Version 5.8). Here's the thing about the Vigor system – it gives each character 2 points, consuming 1 per combat stage. Once you hit 0 Vigor? That character becomes unusable. This completely prevents the old single-team spam strategies we used to rely on.
S15 restricts teams to Pyro, Hydro, and Dendro only. No exceptions. Six Opening Characters (Hu Tao, Thoma, Xingqiu, Nilou, Collei, Baizhu) receive substantial 20% increases to Max HP, Attack, and DEF – which is honestly pretty generous. Special Guest Characters (Iansan, Chasca, Citlali, Ineffa) bypass elemental restrictions entirely and gain double Blessing Level progression.
The difficulty modes escalate quickly: Normal needs 10 characters at Lv.70+, 6 Acts. Hard demands 16 characters, 8 Acts. Visionary? You're looking at 22 characters, 10 Acts. Each additional character grants party-wide buffs: HP +1600, ATK +100, DEF +100, EM +40.
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F2P One-Team Clear Strategy Fundamentals
Here's where things get interesting. F2P clears maximize trial characters and borrowed units through the Supporting Cast system. The key? Use Opening Characters as your primary DPS, supplemented by one borrowed high-investment character from a friend or random player.
Start with Dendro-core teams for Acts 1-3. Bloom reactions provide excellent AoE coverage. Then transition to Pyro-core for Acts 7-10 when you're facing those boss vulnerability windows.
Investment requirements are surprisingly minimal – you need one personal character at 80/90 with 6/6/6 talents as your anchor unit. The rest of your team uses trial characters with pre-built artifacts. Energy Recharge targets become crucial: aim for 180-200% ER on supports, 200% ER on Xingqiu for Vaporize teams.
Your core team structure should include: strong single-target DPS (Hu Tao trial), reliable off-field applicator (Xingqiu/Collei), healer (Baizhu/Yaoyao), and a flexible slot for elemental coverage.
Top F2P Team Compositions for S15
Dendro National Variant: Hu Tao (trial) + Xingqiu (trial) + Collei (trial) + Yaoyao
This composition works beautifully. Hu Tao provides massive single-target damage during those Elemental Skill windows. Xingqiu enables Vaporize while offering damage reduction and healing. Collei applies Dendro for Burning reactions, and Yaoyao offers team healing plus Dendro resonance.
Pseudo-Taser Build: Nilou (trial) + Collei + Baizhu + Xingqiu
The rotation flows like this: Nilou Skill → Collei Burst → Baizhu Skill → Xingqiu Burst → Nilou charged attacks. Generates multiple Bloom cores with solid defensive utility.
Burning Team: Thoma (trial) + Collei (trial) + Baizhu (trial) + Yaoyao
Thoma's Burst provides consistent Pyro application, Collei maintains Dendro aura, Baizhu offers additional Dendro and healing. This setup absolutely excels against Tenebrous Papilla (Act 6) and Lava Dragon Statue (Act 10).
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Character Build Priorities & Investment Levels
Trial characters come with 6/6/6 talents, which is honestly pretty decent. Your personal characters should reach 6/6/6 for about 80% effectiveness potential. Talent priorities vary: DPS characters need Normal Attack > Burst > Skill, while supports want Burst > Skill > Normal Attack.
Artifact main stats matter more than you'd think. Sands should be ATK% for DPS, ER% for supports. Goblet goes Elemental DMG% for DPS, HP% for healers. Circlet wants CRIT Rate/DMG for DPS, Healing Bonus% for healers.
For substats, get CRIT Rate to 60-70% first, then focus CRIT DMG, ATK%, and ER%.
F2P weapon priorities:
Hu Tao: Dragon's Bane > White Tassel
Xingqiu: Sacrificial Sword > Favonius Sword
Collei: Favonius Warbow > Sacrificial Bow
Baizhu: Prototype Amber (craftable, provides energy plus healing)
Optimal Rotations & Energy Management
Vaporize Core Rotation (20-second cycle):
Start with Xingqiu Burst for Hydro aura. Activate Hu Tao Skill for Paramita Papilio state. Execute Hu Tao's 9x Normal + Charged Attack combo. Follow with Hu Tao Burst for healing plus damage. Then Collei Skill + Burst for Dendro application. Finish with Yaoyao Skill for healing plus Dendro.
Burning Focus Rotation (15-second cycle):
Begin with Collei Burst for Dendro field. Activate Thoma Burst for continuous Pyro. Use Baizhu Skill for shield plus Dendro. Trigger Thoma Normal Attacks to proc Burst waves. End with Yaoyao Skill to maintain Dendro and heal.
Energy requirements shift based on scenario. Single-target fights need Xingqiu at 200-220% ER, Collei at 180-200%, Baizhu at 160-180%. Multi-target scenarios reduce these by about 20% each. Favonius weapons on supports generate additional energy – use them liberally.
Stage-Specific Boss Counter Strategies
Act 3 - Maguu Kenki Trio: Group the Galloping Frost Kenki with others by baiting its dash attack toward center. Use Xingqiu's damage reduction, apply Vaporize during grouped phases, save Hu Tao Burst for execute timing.
Act 6 - Tenebrous Papilla: This one's tricky. Requires 53 elemental attacks in 15 seconds to break Void Barrier. Failure causes 60% Max HP + 3000 damage – ouch. Use continuous Burning (Thoma + Collei) since each tick counts as an elemental attack.
Act 8 - Potapo's Solidarity: The Protection Spirit gains power from party healing, then deals massive damage to the boss when charged. Use team-wide healing (Yaoyao/Baizhu) rather than single-target. Coordinate healing bursts with DPS windows for maximum efficiency.
Act 10 - Lava Dragon Statue: Apply Pyro twice for Molten Dragon form, continue for Overburn state. This gives you a 17-second window with reduced resistances. Save your major DPS abilities for this Overburn window.
Common F2P Mistakes & Solutions
Build errors happen frequently. Don't over-invest Normal Attack talents on supports – prioritize Burst/Skill instead. Stop neglecting Energy Recharge; use ER% sands until you achieve 100% Burst uptime. And please don't ignore Elemental Mastery on reaction enablers.
Rotation issues plague many players. Using DPS outside reaction windows wastes potential – establish auras first. Overlapping similar buffs reduces efficiency; stagger them for consistent uptime.
Resource problems stem from spreading investment too thin. Focus on one 4-character core. Don't prioritize weapons over talents either – talents provide guaranteed increases while weapon gacha remains unpredictable.
Resource Management & Upgrade Priorities
Resin allocation should follow this schedule: Weeks 1-2 focus on talent books for main DPS. Weeks 3-4 hit artifact domains. Weeks 5-6 cover weapon materials plus EXP. Weeks 7-8 optimize artifacts.
Daily priorities: talent books (Mon/Thu), weapons (Tue/Fri), artifacts (Wed/Sat/Sun).
Artifact farming priority: Crimson Witch for Hu Tao/Thoma first. Then Emblem domain for Xingqiu/Collei. Finally Deepwood for Dendro supports.
Talent books follow this hierarchy: Gold books for main DPS to level 8. Silver books for support Bursts 6-8. Bronze books for support Normal Attacks.
Performance Benchmarks & Success Metrics
DPS requirements scale significantly. Acts 1-3 need 15,000-20,000 team DPS. Acts 4-6 demand 25,000-30,000 with reactions. Acts 7-10 require 35,000+ during vulnerability windows.
Clear time targets vary by playstyle. Speed runs want Acts 1-3 under 90s, 4-6 under 120s, 7-10 under 180s. Comfortable clears allow Acts 1-6 under 3min, 7-10 under 5min.
Score optimization? Focus bonus objectives aligning with team strengths. Invest Fantasia Flowers in reaction-based Brilliant Blessings. Use trial characters early to preserve Vigor for later acts.
Frequently Asked Questions
Can I clear S15 without 5-star characters?
Absolutely. The trial system provides 5-star Opening Characters with competent builds. Combined with 4-star supports, F2P players achieve full clears using trial characters plus one borrowed unit.
How much investment needed for one-team clears?
Surprisingly minimal. One personal character at level 80 with 6/6/6 talents. Your remaining team uses trial characters, making this strategy accessible for newer players.
Best F2P team for all boss mechanics?
Hu Tao + Xingqiu + Collei + Yaoyao covers everything. Vaporize reactions, Burning for shields, team healing, and sufficient elemental application for all S15 requirements.
Managing energy without multiple Favonius weapons?
Prioritize ER substats and main stats on supports. Use Prototype Amber on catalysts. Fight near enemies for particles, use Skills off-cooldown consistently.
Required constellation levels?
C0 works perfectly for all characters. Trial characters come at C0 with appropriate builds anyway. Focus on rotations and reactions over constellation investment – your wallet will thank you.
Countering Tenebrous Papilla without Natlan characters?
Continuous Burning with Thoma + Collei does the trick. Each Burning tick counts toward those 53 elemental attacks. Maintain the reaction throughout the 15-second window, supplement with Normal Attacks when needed.