No Fall Damage

 if (pThis->m_pBaseEngine->GetConfig()->GetCVar("antifalldamage_active")->GetBool())
    {
        CBaseEntity *pLocalEntity = pThis->m_pBaseEngine->GetLocalPlayer();
        if (pLocalEntity != NULL &&
            pLocalEntity->GetMoveType() != MOVETYPE_NOCLIP &&
            pLocalEntity->GetMoveType() != MOVETYPE_LADDER &&
            !(pLocalEntity->GetFlags() & FL_ONGROUND) &&
            !(pLocalEntity->GetFlags() & FL_PARTIALGROUND))
        {
            CBaseUserCmd *pUserCmd = pThis->m_pHookHandler->GetUserCmd(sequence_number);
            if (pUserCmd != NULL)
            {
                float fFallDamage = (float)((float)(pLocalEntity->GetFallVelocity() -580.0) * 0.23809524);
                if (fFallDamage < 0.0f)
                {
                    trace_t sTrace;
                    CTraceFilterSkipTwoEntities traceFilter(pLocalEntity->GetEntity(), NULL);
                    Vector vecAbsOrigin = pLocalEntity->GetAbsOrigin();
                    Vector vecPredictedAbsOrigin = pLocalEntity->Predict(); // account for next tick
                    pThis->m_pBaseEngine->EngineTrace->TraceRay(vecAbsOrigin, vecPredictedAbsOrigin, 0x4600400B, (ITraceFilter *)&TraceFilter, &sTrace);
                    if (sTrace.fraction != 1.0f)
                        *(DWORD *)pUserCmd->forwardmove() = NAN_VALUE;
                }
            }
        }
    }