A quick cheat sheet for skills from the CRP (aka LRB6) edition of Blood Bowl.  This is intended for coaches familiar with skills and new coaches should always refer to the official CRP rules for a full understanding of a skill.

As a rule of thumb, each re-roll skill may be used only once per turn.
BlockSurvive both downs
DauntlessRoll D6 + ST > oppST to block with equal strength
Dirty Player+1 to fouls (armour or injury)
FendPrevent follow up
FrenzyMandatory 2nd block on push, follow up mandatory
KickCan halve kick scatter
Kick-Off ReturnMove 3 squares at kick off
Pass BlockMove 3 squares when oppponent passes
ProRe-roll any roll on 4+
Shadowing2D - MA + oppMA <=7 to follow
Strip BallPushes dislodge ball
Sure HandsRe-roll pick ups; negates strip ball
TackleNegates dodge skill
WrestleOn both down, place both players prone, ignore block
CatchRe-roll catches
Diving Catch+1 to catch accurate passes; may catch a ball if landing in an adjacent square (excludes bounces)
Diving Tackle-2 to dodge rolls; tackler placed prone in vacated square
DodgeRe-roll dodge rolls; survive push-pow
Jump UpNo stand up penalty; may block from prone on agility roll + 2
LeapJump 2 squares after making an agility roll
Side StepChoose any available square when pushed or knocked over
Sneaky GitIgnore doubles on unsuccessful foul armour rolls
SprintGo for it an extra square
Sure FeetRe-roll go for its
Accurate+1 to passes
Dump-OffCan quick pass when blocked
Hail Mary PassPass anywhere on 2+; can't be intercepted; never accurate
LeaderExtra re-roll per half
Nerves of SteelIgnore tackle zones for pass/catch rolls
PassRe-roll failed passes
Safe ThrowMake agility roll to ignore interception; keep hold of ball for non-1 fumbles
Break TackleDodge with ST instead of AG; once per turn only
GrabPlace opponent anywhere; negates side step
GuardAlways count as assisting
JuggernautOn blitz only; both down as push; negates stand firm, fend and wrestle
Mighty Blow+1 to armour or injury roll
Multiple BlockBlock 2 guys, treat them as +2 ST each
Piling OnRe-roll armour/injury rolls; player placed prone
Stand FirmResist pushes, even when knocked over
Strong Arm+1 to pass rolls, except quick pass
Thick SkullKO only on a 9
Big HandIgnore tackle zones and rain for pick up rolls
ClawsTreat opponents as AV7 when blocking
Disturbing Presence-1 to pass/catch rolls within 3 squares
Extra Arms+1 to pick up, catch, and intercept rolls
Foul Appearance2+ roll required by attackers on blocks
Horns+1 to strength on blitzes
Prehensile Tail-1 to players dodging out
Tentacles2D - ST + oppST <= 5 to hold opponent
Two Heads+1 to dodge rolls
Very Long Legs+1 to intercept and leap rolls; cancels safe throw
Always Hungry2+ to attempt TTM; on 1, 2+ to avoid being eaten
Animosity2+ to pass/hand ball
Ball & ChainMayhem! Scatter to move; auto block
Blood Lust2+ to avoid bloodlust; on bloodlust, either bite team mate (injury roll, badly hurt only) or fly away
BombardierBombs away! Doesn't count as a pass
Bone-Head2+ to act; if failed, tackle zone lost
Chainsaw2+ to use chainsaw; armour roll + 3 instead of block dice; if failed, chainsaw hits self
DecayRoll twice on the injury table
Fan Favourite+1 FAME
Hypnotic GazeAgility roll to hypnotize, -1 modifier per tackle zone
Loner4+ to use rerolls
No HandsNo ball allowed
Nurgle's RotRaise killed opponent as a rotter
Really Stupid2+ to act; 4+ if no team mate to help; if failed, tackle zone lost
RegenerationHeal on 4+
Right StuffCan be thrown
Secret WeaponBanned after play
StabArmour roll instead of block dice; injury roll ignores niggles
Stakes+1 to armour roll when stabbing undead
StuntyNo tackle zone modifiers when dodging; -1 to passing rolls; on injury, 7 is KO, 9 badly hurt
Take Root2+ to avoid take root; on 1, stuck until knocked over
Throw Team-MateOnly quick or short pass; -1 modifier; no turnover on fumble
Titchy+1 to dodges; no -1 modifier to opposing dodges
Wild Animal2+ to act on block/blitz, 4+ otherwise; always has tackle zone