To challenge but not to kill

[bigbaddragon]

Hi all,

Me and my friends have decided to try out Tome of Battle but since there are only three of us we'll mostly be playing arena battles or single shots and only two of us will play while the third will be the DM. The first DMing turn is mine so I'm planning to start them up as prisoners/gladiators fighting in arena for other people amusement and, later on, join them with some NPC to try and escape together. This guy will be ninja/cloistered cleric/shadowbane stalker and his prime purpose will be to cover healbot and skillmonkey roles.

Character creation was with 40 points point buy and starting level is 12th with normal wealth by level (88k). My friends will play:

Warblade 12
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STR 24 +7 (17 base +3 level +4 item)
DEX 18 +4 (16 base +2 item)
CON 16 +3 (14 base +2 item)
INT 14 +2 (14 base)
WIS 15 +2 (13 base +2 item)
CHA 8 -1 (8 base)

HP: 12d12 + 36 = 119hp
AC: 26 (+7 armor, +4 dexterity, +1 natural, +2 deflection, +2 Ring Of Shielding) Touch20, Flat-footed 26 (-2 enlarged)
Attack: Binding Guisarme +1 +20/+15/+10 1d10 + 11 + 1d6(acid)

Fortitude: 13
Reflex: 11
Will: 9 (+3 vs. mind-affecting, +4 Combat Form)

Initiative: +8

Skill Tricks: Twisted Charge, Nimble Charge

Traits: Farsighted(+1 spot, -1 search), Detached (+1 will, -1 reflex)

*Flaw: Shaky
Feats: Improved Initiative, Combat Reflexes, Combat Expertise, Improved Trip (+13, +18 Enlarged), Power Attack, Combat Focus, Combat Stability, Combat Vigor, Close-Quarters Fighting

*Maneuvers:
Ironheart Surge, Death From Above, Sudden Leap, Rabid Bear Strike, Wall Of Blades

*Stances:
Hearing The Air, Leaping Dragon Stance, Tactics of the Wolf

*Equipment:

Head: +2 wisdom
Face: Scout's Headband
Neck: +1 Natural AC
Shoulders: Cloak Of Resistance
Torso: +2 constitution
Armor: +2 mithral Breastplate
Ring: +2 Deflection
Ring: Ring Of Shielding
Bracers: Armbands of Might
Gloves: +2 Dexterity
Belt: +4 Strength, Enlarge 1/day
Boots: Striding & Springing
Weapon: Binding Guisarme

Crystals:
Weapon: Energy Assault (+1d6 acid dmg)
Armor: Mind-Cloaking (+3 vs. mind-affecting)

Triple Weapon Capsule Retainer - 450
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and Unarmed Swordsage 12
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STR 22(16+2+4) DEX 14 CON 16(14+2) INT 14 WIS 20(16+4)

Feats:
Improved Unarmed Strike
Combat Expertise
Improved Trip
Superior Unarmed Strike
Improved Natural Attack
Adaptive Style
Snap Kick

Skill Tricks:
Acrobatic Backstab
Back on Your Feet
Walk the Walls
Extreme Leap

Items:
Headband of Wisdom +4,
Gloves of Mighty Fists +1 (I allowed him to turn Amulet of Mighty Fists into gloves so he can use some augment crystals

plus I reduced the cost to 3000gp),
Vest of Resistance +2,
Bracers of Armor +4,
Belt of Giant Strangth +4,
Boots of Striding and Springing,
Handy Heaversack,
Periapt of Health +2,
Ring of Deflection +1,
Augment Crystals: Lesser Energy Assault - Electricity; Witchlight Reservoir; Lesser Crystal of Life Drinking x2,
Bag of Flames,
Blessed Bandages x10;
Survival Pouch;
Magic Bedroll;

Manuevers:

1. Burning Blade; Counter Charge; Mighty Throw; Shadow Blade Technique;
2. Flashing Sun;
3. Devastating Throw; Bonecrusher; Death Mark;
4. Searing Charge; Hand of Death; Comet Throw;
5. Soaring Throw; Blodletting Strike; Elder Mountain Hammer Strike
6. Greater Insightful Strike; Balista Throw; Irresistible Mountain Strike;

Stances:

1. Stonefoot Stance; Step of the Wind
3. Assassin's Stance
5. Giant's Stance
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They are both humans and are allowed one flaw and two traits from Unearthed arcana.

What I need from you is to help me choose the enemies so the fights are chalenging but not overwhelming, I don't want their characters to die due to my mistakes or exaggeration. Both of them have Improved Trip feat so I will have to come up with some opponents that are able to withstand that (don't get me wrong here, I'm not trying to make their arch enemies, just a few who will be resistant to their main tactics). Ninjas, something larger than medium, "get back on your feet "skill tricks and that feat that lets you make balance check to remain on your legs come to mind. Other than that what would you suggest me? Any advice will be appreciated. Thanks in advance.

EDIT: Spoilers added.

 

[Jack Simth]

Fundamentally, you can't (unless you fudge the dice), due to the "unlucky dice" (alternately, statistics catching up with someone) issue. A lucky crit on the part of an opponent means that the challenge you expected to pose is overwhelming rather than merely strong. A few of them and you've got a dead PC.

You can come close with larger numbers of weaker opponents - a two on two fight (your two PC's at 12th vs. two NPC's at 11th, or two glass-cannon monsters at CR 10 or 11) can do it, as can using four opponents (at CR 8 or 9, focus on things that don't play too harshly to your PC's weaknesses).

 

[Angrydad]

Go for monsters with more than two legs or that are legless, like snakes or some such thing, to counter the trip tactic. Also, give them encounters with larger numbers of weaker monsters as opposed to one powerful monster, unless it's a big showdown type scenario. If there's lots of enemies to deal with/plow through, it can be more satisfying even though they're not getting much XP for it.